02. Chemical and cellular basis of life Flashcards
(518 cards)
1
Q
How many elements are recognized in nature?
A
92 elements
2
Q
How many elements are essential for human life?
A
~25 elements
3
Q
How many elements are essential for plant life?
A
~17 elements
4
Q
Name the four main elements in living matter
A
- Oxygen
- Carbon
- Hydrogen
- Nytrogen
Makes up 96% of living matter
Acronym : CHON
5
Q
Which elements make up the most of remaining 4% of living matter (apart from C, H, O and N)?
A
- Calcium (Ca)
- Phosphorus (P)
- Potassium (K)
- Sulphur / Sulfur (S)
6
Q
Which elements are contained in minute amounts in living matter?
A
- Sodium (Na)
- Chlorine (Cl)
- Magnesium (Mg)
- Boron (B)
- Cobalt (Co)
- Copper (Cu)
- Chromium (Cr)
- Fluorine (F)
- Iodine (I)
- Iron (Fe)
7
Q
Give two reasons on why water is important for life
A
- Vital chemical constituent of living cell
- Provides a biological medium for all organisms
8
Q
What are the characteristics of water molecule?
A
Small, polar and angular
9
Q
What’s known as polarity?
A
An uneven charge distribution within a molecule
10
Q
What’s a hydrogen bond in water?
A
Weak attractions between the slightly polar hydrogen atom of one molecule and the slightly polar oxygen atom of adjacent water molecule
11
Q
What’s the bond angle of a water molecule?
A
104.5°
12
Q
What type of bond plays major role in maintaining all the properties of water?
A
Hydrogen bonds (H-O)
13
Q
What are the four major properties of water to maintain life on earth?
A
- Cohesive behavior
- Ability to moderate temperature
- Expansion upon freezing
- Versatility as a solvent
14
Q
What’s known as cohesion in water molecules?
A
Attraction between water molecules due to hydrogen bonding
15
Q
What’s known as adhesion in water molecules?
A
Attractions between water molecules and other substances
16
Q
Give an example of using cohesion for life functions
A
Water and dissolved substances such as minerals are transported as a continuous column through xylem against gravity.
17
Q
Give an example of using adhesion for life functions
A
Adhesion between water molecules and cell walls helps in conduction of water and dissolved materials.
18
Q
Why does water have a high surface tension?
A
Due to cohesion between water molecules
In an aquatic system, upper surface water molecules are attracted by lower surface molecules and it forms a water film.
19
Q
How does water’s ability to moderate temperature can help living organisms?
A
- Due to the high specific heat, water will function as a thermal buffer in living systems and aquatic bodies during temperature fluctuations.
- Due to the high heat of vaporization, with a minimum loss of water an organism can release much heat energy.
- Evaporation of sweat form human skin help to maintain body temperature at a constant level.
- Transpiration in plants helps to cool the plant body surface and prevent from becoming too warm in the sunlight.
20
Q
At which temperature does water has the maximum density?
A
4°C
21
Q
Water is good as a solvent due to its which characteristic?
A
Polarity
22
Q
Which molecules and compounds can dissolve in water?
A
- Polor molecules (Glucose)
- Ionic compounds (NaCl)
- Molecules with both polar and ionic regions (lysozymes)
23
Q
What are the main organic compounds of organisms?
A
- Carbohydrates
- Lipids
- Proteins
- Nucleic acids
24
Q
Which factor is essential for solubility of the solutes?
A
Polarity
25
What's the most abundant group of organic compounds?
Carbohydrates
26
What's the elemental composition of carbohydrates?
- Carbon (C)
- Hydrogen (H)
- Oxygen (O)
Acronym : CHO
27
What's the general formula of carbohydrates?
Cx(H2O)y
28
Name the three major groups of carbohydrates
- Monosaccharides
- Disaccharides
- Polysaccharides
29
Which corbohydrates are considered as **sugars**?
Monosaccharides and disaccharides
30
What's simplest form of carbohydrates?
Monosaccharides
31
What's the molecular formula of monosaccharides?
(CH2O)n
32
How many C atoms can be a part of a monosaccharide?
3-7
33
What are some characteristics of monosaccharides?
- Reducing sugars
- Water soluble
- Occur in crystalline form
34
Monosaccharides with 3 carbon atoms are names as?
3C - Triose
35
Give an example for triose sugars
Glyceraldehydes
*(Phosphoglyceraldehyde is a derivative of triose)*
36
Give an example for a monosaccharide with 4 carbon atoms
4C - Tetroses
37
Give an example for a monosaccharide with 5 carbon atoms
5C - Pentoses
38
Give an example for a monosaccharide with 6 carbon atoms
6C - Hexoses
39
Phosphoglyceraldehyde is a derivative of which type of monosaccharide?
Triose (Glyceraldehydes)
40
Give an example for a tetrose
Erythrose (rare in nature)
41
Give examples for monosaccharides related to pentose
- Ribose
- Deoxyribose
- Ribulose (RUBP)
42
**RUBP** is a derivative of which monosaccharide?
Ribulose
43
Give examples for hexoses
- Glucose
- Fructose
- Galactose
44
What's a **carbonyl group**?
A carbon atom double bonded to an oxygen atom
A **C=O** bond
45
What are sugar types which are classified according to the type of carbonyl group?
Aldo - Alodoses
Keto - Ketoses
46
Keto and Aldo groups are types of which group?
Corbonyl C=O
47
What's an **aldehyde group**?
A corbonyl group with the C atom attached to a H atom
48
What's a **keto group**?
A carbonyl group in which the C atom is bonded to C atoms (not H)
49
Give some examples for sugars (monosaccharides*) which belong to **aldoses**
- Glucose
- Galactose
50
Give some examples for sugars (monosaccharides*) which belong to **ketoses**
Fructose
51
Some monosaccharides are in which form when in an aqueous media?
Ring form
52
How are **disaccharides** formed?
By joining two monosaccharides by a **glycosidic bond**
53
What's a **glycosidic bond**?
Glycosidic bonds are covalent bonds that connect a sugar molecule to another molecule, such as another sugar or a non-sugar compound, through the linkage of their respective hydroxyl groups.
54
How's a **glycosidic bond** is formed?
It's formed by removal of a water molecule from two adjacent monosaccharides by a condensation reaction (dehydration synthesis).
55
Which disaccharide is formed by the condensation of two glucose molecules?
Maltose
56
Which disaccharide is formed by the condensation of glucose and fructose molecules?
Sucrose
57
Which disaccharide is formed by the condensation of glucose and galactose molecules?
Lactose
58
What are **reducing sugars**?
Reducing sugars are groups of sugars which have a free aldehyde group or a keto group, which can reduce other compounds.
59
Give examples for reducing sugars
- Glucose
- Fructose
- Galactose
- Maltose
- Lactose
*(basically all the example that were in grade 10 text book except for sucrose)*
60
Give an example for a **non-reducing** sugar
Sucrose
*sucrose doesn't have a free aldo/keto group*
61
Which type of carbohydrates are **macromolecules** and **biopolymers**?
Polysaccharides
62
What are the characteristics of polysaccharides?
- Non-crystalline
- Water insoluble
- Not considered as sugars
63
What are the functions of polysaccharides in living organisms?
- Functioning as a storage component
- Contributing to the structure of living organisms
64
Polysaccharides which facilitate to the structure of living organisms are known as?
Structural polysaccharides
65
Polysaccharides which acts as a storage component are known as?
Storage polysaccharides
66
Name few storage polysaccharides
Starch, Glycogen
67
Name structural polysaccharides
Cellulose, Hemicellulose, Pectin
68
What are the two forms of polysaccharides based on their structure/ architecture?
- Linear forms
- Branched forms
69
Give some examples for linear forms of polysaccharides
Cellulose, Amylose
70
Give some examples for Branched forms of polysaccharides
Glycogen, Amylopectin, Hemicellulose
71
What's the monomer of starch?
Glucose
72
What's the monomer of glycogen?
Glucose
73
What's the monomer of cellulose?
Glucose
74
What's the monomer of inuline?
Fructose
75
What's the monomer of pectin?
Galacturonic acid
76
What's the monomer of hemicellulose?
Pentose and hexoses
77
What's chitin?
It's a nitrogen containing polysaccharide
78
What's the monomer of chitin?
Glucosamine
79
What's the function of starch?
Storage of foods in plants
80
What's the function of glycogen?
Storage of food in animals and fungi
81
What's the function of cellulose?
Component of cell wall
82
What's the function of inuline?
Food storage in tubers of dhalia
83
What's the function of pectin?
Component of middle lamella of plant cell wall
84
What's the function of hemicellulose?
Component of plant cell wall
85
What's the function of chitin?
Component of fungal cell walls and exoskeleton of arthropods
86
Name polysaccharides which are responsible for the structure of plant cells
Cellulose, Hemicellulose, Pectin
87
What are the functions of monosaccharides?
- Energy source
- Building blocks of disaccharides and polysaccharides
- Components of nucleotides
88
What are the functions of disaccharides?
- Storage sugar in milk - Lactose
- Translocation in phloem - Sucrose
- Storage sugar in sugarcane - Sucrose
89
Which carbohydrate is responsible for food storage in milk?
Lactose
90
Which carbohydrate is associated with translocation in phloem?
Sucrose
91
Which carbohydrate is associated with storage of food in sugarcane?
Sucrose
92
Name some functions of storage polysaccharides
- Storing glucose as energy source in plants and chlorophytes - Starch
- Storing glucose as energy source in plants and fungi - Glycogen
- Storing fructose as energy source in Dhalia tubers - Inuline
93
What are the functions of structural polysaccharides?
- Cellulose in the cell walls of plants and chlorophytes
- Hemicellulose in cell walls of plants
- Pectin in the middle lamella of plant tissues
- Chitin in cell walls of fungi and in exoskeleton of arthropods
94
What are the characteristics of lipids?
- Diverse group of hydrophobic molecules
- Large biological mecules but not considered as polymers or macromolecules
- Consist of C, H, O and H:O ratio is not 2:1. Comparatively more H than O are present
95
Give examples for biologically important types of lipids
Fats, Phospholipids and Steroids
96
What are the components of fat?
Glycerol and fatty acids
97
Which chemical group does glycerol belong to?
Alcohol
98
Explain the structure of a glycerol molecule
Glycerol has 3 carbon atoms where each of them is bonded to a hydroxyl group
99
Explain the structure of fatty acids
Fatty acids are hydrocarbon chains with long carbon skeleton with a carboxyl group at its one terminal
100
How many carbon atoms are in a fatty acid molecule?
Usually 16-18
101
By which bond does fatty acid bind to each hydroxyl group of glycerol?
Ester bond
102
What's the resulting fat molecules are called by the bonding of glycerol and 3 fatty acids?
Triacylglycerol (Triglycerides)
103
Which component contribute to the hydrophobic nature of fats?
Non-polar hydrocarbon chains of fatty acids
104
What are the two types of fats based on the nature of hydrocarbon chains?
- Saturated fats
- Unsaturated fats
105
What are **saturated fats**?
Fats which are made up of saturated fatty acids with hydrocarbon chains having no double bonds
106
Which fats come under saturated fat category?
Animal fats
107
Saturated fats are [...] at room temperature
Solid
108
What are **unsaturated fats**?
Fats which are made up of unsaturated fatty acids with hydrocarbon chains having one or more double bonds
109
Give an example for unsaturated fat
Plant oils
110
Unsaturated fats are mostly [...] in room temperature
Liquid
111
What are the two types of unsaturated fats, based on the nature of their double bonds?
- Cis unsaturated fats
- Trans unsaturated fats
112
Excess consumption of which fats are contributing to atherosclerosis?
Saturated fats and trans unsaturated fats
113
Phospholipids are major components of which part of the cell?
Cell membrane
114
Phospholipids are composed of?
Glycerol, 2 fatty acids, phosphate group + additional polar molecule ie. Choline
115
Which part gives a negative charge to the phospholipid molecule?
Phosphate group
116
Which part of the phospholipid is hydrophilic?
Phosphate group and it's attachment (head)
117
Which part of the phospholipid is hydrophobic?
Hydrocarbon tails
118
What are the functions of lipids?
- Food reserve as an energy source
- Found as components of cell membrane
- Maintain the fluidity of plasma membrane
- Act as signaling molecules that travel through body
119
Which type of lipids are responsible for storing food?
Triacylglycerols such as fats and oils
120
Which types of lipids are responsible for maintaining the fluidity of plasma membrane?
Phospholipids and cholesterol
121
Which lipids are found as a component of cell membrane?
Phospholipids and cholesterol
122
Which type of lipids act as a signaling molecule?
Hormones
123
What's the monomer of proteins?
Amino acids
124
How many unique amino acids are involved in protein formation?
20
125
What's the elemental composition of proteins?
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
- Sulfur
Acronym : CHONS
126
What's at the center of the amino acid?
An asymmetric carbon atom
127
Which amino acid does not have an asymmetric carbon atom at the center?
Glycine
128
What are the components of an amino acid?
Asymmetric carbon atom, an amino group, a carboxyl group, a hydrogen atom and a variable group (side chain) symbolized by "R"
129
What's the R group of glycine?
A hydrogen atom
130
What's the R group of an amino acid?
Side chain (Differs with each amino acid)
131
What's the backbone of an amino acid?
All the other components except for the R group
132
Amino acids may have one or more [...] and [...]
Carboxyl groups
Amino groups
133
Amino groups has [...] nature
An alkaline
134
Carboxyl group is [...] in nature
Acidic
135
What's the term refered to molecule which have both alkaline and acidic nature?
Amphoteric molecules
136
Amino acids are [...] in nature
Amphoteric
137
What's the bond which forms between amino acids?
Peptide bond (C—N)
138
Which type of reaction amino acids undergo to create a peptide bond?
A condensation reaction (dehydration synthesis)
*removes a water molecule*
139
Protein is composed of one or more [...] which are composed of [...].
Polypeptide chains
Amino acids
140
What are the levels of protein structure?
1. Primary structure
2. Secondary structure
3. Tertiary structure
4. Quaternary structure
141
What's known as the **primary structure** of proteins?
The unique sequence of linearly arranged amino acids linked by peptide bonds
142
What's known as the **secondary structure** of proteins?
Further folding and coiling of the primary structure of a single polypeptide chain
143
What's causes the secondary structure of proteins?
Intramolecular hydrogen bonds between the oxygen atoms of the carboxyl groups and hydrogen atoms of the amino groups of the same polypeptide chain backbone
144
Name the two types of secondary protein structure
- Alpha helix
- Beta pleated sheet
145
Give an example for alpha helix type of secondary protein structure
Keratin
146
Give an example for beta pleated sheet type of secondary protein structure
Spider's silk fiber
147
What's the **tertiary structure** of proteins?
Usually the secondary polypeptide chain bends and folds extensively forming a precise **compact, unique, functional** and **three-dimensional** shape
148
Interactions between [...] of amino acids causes the tertiary structure of proteins
Side chain/ R-group
149
What are the interactions between side chain/ R-group that results in tertiary structure?
- H bonds
- Disulfide bonds
- Ionic bonds
- Hydrophobic interactions and Van Der Waals interactions
150
Give examples for the tertiary structure of proteins
- Most of the enzymes
- Myoglobin
- Albumin
151
What's the **quaternary structure** of proteins?
Aggregation of two or more polypeptide chains involve in the formation of one functional protein (tertiary structure)
152
What's the term refered to separate chains of the tertiary structure of proteins?
Protein subunits
153
In the tertiary structure of proteins, subunits are held together by [...] interactions
Inter and intra-molecular
154
Give examples for the quaternary structure of proteins
Hemoglobin, Collagen
155
What are the protein subunits related to adult human RBCs?
- 2 alpha subunits
- 2 beta subunits
- Heme group in each of the alpha & beta subunits
- Fe ion in the middle of heme groups
156
What's known as the **denaturation of proteins**?
The loss of specific three dimensional shape due to the alteration of weak chemical bonds and interactions
157
What are the agents affecting **denaturation** of proteins?
1. High temperature and high energy radiation
2. Strong acids alkaline and high concentration of salts
3. Heavy metals
4. Organic solvents and detergents
158
What's the function of **catalytic proteins**?
Catalyzing biochemical reactions
159
Give examples for **catalytic proteins**
Pepsin, amylase
160
What's the function of **structural proteins**?
- Preventing desiccation
- Providing strength and support
161
Give examples for **structural proteins**
Keratin, collagen
162
What's the function of **storage proteins**?
- Storage protein in egg
- Storage protein in milk
163
Give examples for **storage proteins**
Ovalbumin, Casein
164
What's the function of **transport proteins**?
- Transport O2 and CO2
- Transport fatty acids
165
Give examples for **transport proteins**
Hemoglobin, serum albumin
166
Write a function of proteins which act as a hormone
Regulating blood glucose level
167
Give examples for proteins which function as a hormone
Insulin, Glucagon
168
Write a function of contractile/motor proteins
Contraction of muscle fibers
169
Gve examples for **contractile/motor** proteins
Actin, myosin
170
What's the function of **defensive proteins**?
Neutralizing foreign bodies
171
Give an example for a **defensive protein**
Immunoglobulins (Antibodies)
172
Give examples for proteins which **catalyzes biochemical reactions**
Pepsin, Amylase
173
Give an example for a protein which functions to **prevent desiccation**
Keratin
174
Give an example for a protein which **provides support and strength**
Collagen
175
Which protein functions as the **storage protein in egg**?
Ovalbumin
176
Which protein functions as the **storage protein in milk**?
Casein
177
Which protein is responsible for the **transmission of O2 and CO2?**
Hemoglobin
178
Which protein is responsible for **transporting fatty acids**?
Serum albumin
179
Which proteins function to **contract muscle fibres**?
Actin, Myosin
180
What are **nucleic acids**?
Polymers which exist as polynucleotides made up of monomers called nucleotides
181
What's the monomer of nucleic acids?
Nucleotide
182
What's the elemental composition of nucleotides?
- Carbon
- Oxygen
- Hydrogen
- Nitrogen
- Phosphorus
Acronym : CHONP
183
Nucleic acids are [...] and [...].
Biopolymers, macromolecules
184
Whata re the two types of nucleic acids?
DNA and RNA
185
What does DNA stand for?
Deoxyribo Nucleic Acid
186
What does RNA stand for?
Ribonucleic Acid
187
What are the components of nucleotides?
- Phosphate group
- Pentose sugar
- Nitrogenous base
188
What's the term used to refer nucleotides without a phosphate group?
Nucleoside
189
Give examples for nucleosides
Adenosine, Guanosine
190
What are the two types of pentose sugar?
Deoxy Ribose & Ribose
191
What's the difference between deoxyribose and ribose?
In deoxyribose, one oxygen atom is less than in ribose
192
What are the two major groups of nitrogenous bases?
1. Purines
2. Pyrimidines
193
What's the characteristic of **purines**?
Larger in size with two rings
194
What's the characteristic of **pyrimidines**?
Smaller in size with a single ring
195
Give examples for purines
Adenine, Guanine
196
Give examples for **pyrimidines**
Thymine, Cytosine, Uracil
197
Which component of nucleotide is responsible for it's acidic nature?
Phosphate group
198
What's the bond between nucleotides in a polynucleotide chain?
Phospho-di-ester bond
199
How does the phospho-di-ester bond form polynucleotides?
By condensation between the -OH of the phosphate of one nucleotide and the -OH attached to the 3rd carbon of pentose sugar of the other nucleotide
200
What's the linear polymer of nucleotides?
Nucleic acids
201
The type of the nucleotide is dependent upon it's which component?
By the type of sugar molecule
202
What are the nitrogenous bases related to DNA?
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
203
What are the nitrogenous bases related to RNA?
Adenine (A)
Uracil (U)
Guanine (G)
Cytosine (C)
*In RNA, there's Uracil (U) instead of Thymine (T)*
204
Which model explains the structure of DNA molecule?
Watson and Crick model
205
Why do DNA molecule have a **double helix** shape?
Because DNA molecules have two anti-parallel polynucleotide chains that spiral around an imaginary axis
206
Why does the arrangement of DNA molecule is referred to as **anti-parallel**?
Because the two sugar-phosphate backbones run in opposite direction of each other
207
How the two strands of DNA is held together in it's double helix shape?
By hydrogen bonds between the paired nitrogen bases
208
What's the **base pair rule** in nucleotide base pairing?
A purine base, pairs with a specific pyrimidine base
209
What nitrogenous base does adenine (purine) bind to in DNA?
Thymine (pyrimidine)
(A-T)
(G-C)
210
Which nitrogenous base does guanine (purine) bind to?
Cytosine (pyrimidine)
(A-T)
(G-C)
211
How many hydrogen bonds are there between A-T bond?
2
212
How many hydrogen bonds are there between G-C bond?
3
213
Name the complementary base pairs in DNA
Adenine—Thymine (2 H bonds)
Guanine—Cytosine (3 H bonds)
214
How many base pairs are there in a complete turn of the original double helix structure?
10 base pairs
215
What's the function of DNA?
- Store the genetic information required for protein synthesis
- Store and transmit genetic information from one generation to the next generation
216
Which nucleic acid is normally a single stranded one?
RNA
217
What are the nitrogenous bases which RNA consists of?
Adenine, Uracil, Guanine, Cytosine
218
Does complementary base pairing occur in RNA?
Complementary base pairing between two RNA molecules or within the same molecule may occur in some.
219
Name the complementary base pairs of RNA
Adenine—Uracil (2 H bonds)
Guanine—Cytosine (3 H bonds)
(A-U)
(G-C)
220
How many H bonds are there in A-U bond in RNA?
2
221
How many H bonds are there in G-C bond in RNA?
3
*same as in dna because this is the same bond*
222
Which facility is provided by the complementary base pairing in RNA?
It facilitates three-dimentional shapes essential for RNA's functioning
223
What are the three types of RNA present in cells?
1. Messenger RNA
2. Transfer RNA
3. Ribosomal RNA
224
What does **mRNA** stand for?
Messenger RNA
225
What does **tRNA** stand for?
Transfer RNA
226
What does **rRNA** stand for?
Ribosomal RNA
227
What's the least abundant type of RNA?
Messenger RNA - mRNA
228
mRNA is a [type of the polymer] molecule
Linear
229
What are the functions of mRNA?
- Copies the genetic information stored in DNA molecule as a sequence of nitrogenous bases
- Transports genetic information from nucleoplasm to the site of protein synthesis (ribosome) through nucleopores
230
What's the site of protein synthesis?
Ribosome
231
What's the smallest type of RNA molecules?
Transfer RNA - tRNA
232
What's the structure of tRNA?
- Linear
- Forms three looped structures
233
What's the function of tRNA?
Transportation of amino acids to the site of protein synthesis
234
What's the most abundant type of RNA?
Ribosomal RNA - rRNA
235
rRNA has a [define structure] structure
Complex, irregular
236
What's the function of rRNA?
Provides the site where polypeptide chains are assembled
237
What are the differences between DNA and RNA?
1. DNA is a double stranded molecule while RNA is a single stranded molecule
2. DNA consists of A, T, G and C while U is absent and RNA consists of A, U, G and C while T is absent
3. Sugar molecule in DNA is deoxyribose, while in RNA it's ribose
238
Name some nucleotides other than those found in nucleic acids
- ATP
- NAD+
- NADP+
- FAD
239
What does **ATP** stand for?
Adenosine Triphosphate
240
What does **NAD+** stand for?
Nicotinamide Adenine Dinucleotide
241
What does **NADP+** stand for?
Nicotinamide Adenine Dinucleotide Phosphate
242
What does **FAD** stand for?
Flavin Adenine Dinucleotide
243
What's the function of ATP?
Universal energy carrer
244
What are the functions of NAD+?
- Acts as a coenzyme
- Act as an electron carrier
- Functions as an oxidizing agent during respiration
245
What are the functions of NADP+?
- Acts as coenzymes
- Act as an electron carrier
- Functions as an oxidizing agent during photosynthesis
246
What are the functions of FAD?
- Act as a coenzyme
- Act as an electron carrier
- act as an oxidizing agent
247
Which type of RNA brings amino acids to the site of protein synthesis?
tRNA
248
Which type of RNA has a complex irregular structure?
rRNA
249
Which nucleotide functions as an oxidizing agent during respiration?
NAD+
250
Which nucleotide act as an oxidizing agent in photosynthesis?
NADP+
251
What's known as **cytology**?
Cell biology
252
How many lenses does the simplest light microscope has?
Single lense
253
What are the important parameters when it comes to a microscope?
Magnification, Resolution power
254
What's known as magnification in microscopy?
The ratio of object's image size to its actual size
255
What's the maximum magnification of light microscope in general?
×1000 times the specimen
256
What's known as **resolution power** in microscopy?
Minimum distance between two points that can be distinguished as separate points
*(A measure of the clarity of the image)*
257
What's the resolution power of light microscope?
0.2um
258
Magnification is limited due to [...]
resolution
259
What are the lenses of a light microscope?
Objective lense, eye piece
260
Light microscope has a limited resolution due to which property?
The wavelength of light
261
The resolution power is [...] to the wavelength
inversely proportional
262
Why dows electron microscope has larger magnification?
Because it uses a beam of electrons which has a shorter wavelength relative to light
263
What's the magnification of an electron microscope?
5 × 105 times
264
What's the resolution of an electron microscope?
2 nm
265
What are the two types of electron microscopes?
- Transmission Electron Microscope (TEM)
- Scanning Electron Microscope (SEM)
266
For what study does TEM is used?
Used to study the internal structure of the cells
267
When using a TEM, a [...] specimen is used and the specimens are stained with [...]
very thin, heavy metals
268
When using a SEM, specimen is mostly coated with [...] prior to observation
gold
269
For which function SEM is ideal for?
To observe the surface view in three-dimensional appearances
270
In SEM, a fine beam of electrons is [...] from the surface of specimen
reflected
*whereas in TEM, the electron beam goes through*
271
What are the differences between light and electron microscopes?
1. - Glass lenses are used to focus the light rays
- Powerful magnets are used to focus beam of electrons
2. - Image is directly detected by the naked eye
- Micrographs are used
3. - Living and non-living objects can be observed
- Only non-living objects are observed
4. - Actual color of the object can be observed
- Actual color cannot be observed
5. - Dyes used to stain the object
- Heavy metals are used to stain the object
272
What's the basic structural and functional unit of life?
The cell
273
Who first examined cells and coined the term "**cells**"?
Robert Hooke (1665)
274
Who is the first person to **describe and record living single celled organisms**?
Anton Van Leeuwenhook (1650)
275
Which single celled organisms were observed by Anton Van Leeuwenhook?
Euglena & Bacteria
276
What was the conclusion of **Matthias Schleiden** after studying plant tissues?
All plants are made up of cells
277
What was the conclusion of zoologist **Theodore Schwann** about cells?
Animal tissues are made up of cells
278
What was the **Rudolf Virchow**'s theory about cells?
All cells arise from pre-existing cells by cell devision
279
Who concluded that '*animal tissues are made up of cells*'?
Theodore Schwann
280
Who showed that '*all cells arise from pre-existing cells*'?
Rudolf Virchow
281
Who concluded that '*all plants are made up of cells*'?
Matthias Schleiden
282
Name the scientists who presented the **cell theory**
- Matthias Schleiden
- Theodore Schwann
- Rudolf Virchow
283
What are the statements in **cell theory**?
1. All organisms are composed of one or more cells
2. The basic structural and functional unit of organisms is the cell
3. All cells arise from pre-existing cells
284
What are the two kinds of cellular organization?
- Prokaryotic
- Eukaryotic
285
What are the basic features which all cells share?
- All cells are bounded by a plasma membrane which is a selective barrier
- Within the cell have, a semifluid, jelly like substance called **cytosol** *(subcellular components are suspended within the cytosol)*
- Carry DNA as genetic materials
- Ribosoms are found in all cells
286
What's are the organisms that belong to prokaryotes?
Bacteria & Archaebacteria
287
What are the organisms that belong to eukaryotes?
Protists, Fungi, Plants, Animals
288
What's the diameter of a prokaryotic cell?
0.5 - 5 *u*m
289
What's the diameter of a eukaryotic cell?
10 *u*m - 100 *u*m
290
What's the main form of prokaryotic cells?
Unicellular
291
What's the main form of eukaryotic cells?
Multicellular
292
When did the evolutionary origin of prokaryotes happened?
3.5 billion years ago
293
When did the evolutionary origin of eukaryotes happened?
1.8 billion years ago
(evolved form prokaryotes)
294
How does a prokaryotic cell devide?
Binory fission
*No mitosis and meiosis*
295
How does an eukaryotic cell devide?
Mitosis, Meiosis or both
296
How genetic materials are stored in the prokaryotic cell?
Nucleoid, DNA is circular and lies free in the cytoplasm. DNA is not associated with Histone proteins
297
What the region in prokaryotic cell which houses it's free and circular DNA?
Nucleoid
298
Which type of cell's DNA is associated with Histone proteins?
Eukaryotic cell
299
How genetic materials (DNA) are stored in eucaryotic cell?
DNA is linear and contained in nucleus.
**Associated with Histone proteins**
300
What's the type of ribosomes that are in prokaryotic cells?
70s ribosomes (smaller)
301
What's the type of ribosomes that are in eukaryotic cells?
Both 70s and 80s
- 70s : mitochondria and chloroplast
- 80s : larger
(may attach to ER or freely available in cytosol)
302
What are the characteristics of organelles in prokaryotic cells?
- No membrane bound organelles are present
- Consists of few subcellular components
- Internal membranes scarces
*(Usually associated with respiration, photosynthesis or N2 fixation*
303
Usually internal membranes are scarce in prokaryotic cells. If they do exist, they're associated with which functions of the prokaryotic cell?
- Respiration
- Photosynthesis
- N2 fixation
304
What are the characteristics of organelles in eukaryotic cells?
- Membrane bound organelles and other subcellular components are present
305
What are the organelles in eukaryotic cells that are bounded by two membranes?
- Nucleus
- Mitochondria
- Chloroplasts
306
What are the organelles in eukaryotic cells that are bounded by a single membrane?
Lysosomes & Vacuole
307
What are the structural characteristics of prokaryotic cell walls?
- Peptidoglycan present in bacteria and cyanobacteria
- Polysaccharides and protein are present in archaebacteria
308
Which organism types have Peptidoglycan in their cell walls?
Bacteria and Cyanobacteria (Prokaryotes)
309
Which type of organisms have polysaccharides and proteins in their cell wall?
Archaebacteria (Prokaryotic)
310
Cell walls of [...] and [...] are rigid and contain polysaccharides
Green plants, fungi
311
Plant cell walls are composed of [...] and [...]
Polysaccharides and cellulose
312
Fungal cell walls are composed of [...] and [...]
Polysaccharides and chitin
313
What are the characteristics of eukaryotic cell wall?
- Cell walls of green plants and fungi are rigid
- Contain polysaccharides
- Plant cells have cellulose and fungal cell walls have chitin
314
What's the structure of prokaryotic flagella?
- Simple
- Lacking microtubules
- Extracellular (*Not enclosed by cell surface membrane*)
- 20 nm in diameter
315
What's the diameter of a prokaryotic flagellum?
20 nm
316
What are the characteristics of an eukaryotic flagellum?
- Complex
- '9+2' arrangement of microtubules
- Intracellular (*Sorrounded by cell surface membrane*)
- 200 nm in diameter
317
What's the diameter of an eukaryotic flagellum?
200 nm (10x the prokaryotic diameter)
318
How does respiration occur in prokaryotic cells?
Mostly by internal membrane foldings
319
How does respiration occur in eukaryotic cells?
Mitochondria for aerobic respiration
320
What are the photosynthesis related characteristics of prokaryotic cells?
- No chloroplasts
- Takes place on membranes which shows no stacking
321
How's the photosynthetic process carried out in eukaryotic cell?
Chloroplast containing membranes which are usually stacked in to lamellae or grana
322
Which cell type has the ability to fixate nitrogen?
Some prokaryotic cells
323
Does eukaryotes has the ability to fixate nitrogen?
No
324
Which domains belon to prokaryotes?
Bacteria and archaea
325
What's the outer limit of cytoplasm?
Plasma membrane
326
All cellular membranes resemble the ultra structure of [...]
Plasma membrane
327
Who came up with the **fluid mosaic model** (1972) of cell membrane?
Singer and Nicolson
328
What's the most abundant type of lipid in the plasma membrane?
Phospholipid
329
What are **fluid mosaic model** of cell membrane is composed of?
- Phospholipids
- Proteins
330
What are the features of the plasma membrane?
- ~7nm in thickness
- Mainly made up of phospholipid bilayer
- Phospholipids are **amphipathic** molecules
331
Explain the orientation of phospholipids in plasma membrane
- Hydrophilic heads of the phospholipids face outwards towards the aqueous environment of both inside and outside of the cell
- The hydrophic carbon tails face inwards and creates a hydrophobic interior
332
Plasma membrane is compared to the [...]
Fluid mosaic model
333
What are **integral proteins**?
Protein molecules that are randomly embedded in the plasma membrane to contribute to it's mosaic nature
*IMP : Intergral Membrane Proteins*
334
Name the two types of **IMPs**
- Transmembrane proteins
- Peripheral proteins
335
What are **transmembrane proteins**?
Intergral proteins which penetrate all the way through the plasma membrane
336
What are **Peripheral proteins**?
Intergral proteins which are losly bound to the surface of the plasma membrane
(Not embedded in the lipid bilayer)
337
What are **glycoproteins**?
Proteins with a short branching carbohydrate chains like antennae
(aka Glycopeptides)
*any of a class of proteins which have carbohydrate groups attached to the polypeptide chain*
- Oxford Dict.
338
What are **glycolipids**?
Lipids with short branching carbohydrate chains like antennae
*Glycolipids are lipids with a carbohydrate attached by a glycosidic bond*
339
Animal cell membrane may contain few [...] randomly integrated into the phospholipid bilayer
Cholesterol molecules
340
What's the function of cholesterol in the plasma membrane?
Providing rigidity and stability
341
Write down functions of the **plasma membrane**
1. Separating the intra and extracellular environments of the living cell
2. Regulating the exchange of material due to selective permeability
3. Proteins in the plasma membrane enable cell recognition
4. Some proteins in the plasma membrane act as receptor molecules for specific biochemicals
5. Some proteins in the plasma membrane help maintain the shape of the cell
6. Some proteins in the plasma membrane act as enzymes
- Plasma membrane sorround the cytoplasm of living cell, physically separating the Intracellular environment from the extracellular environment
- Plasma membrane is selectively permeable and able to regulate the exchange of material needed for survival
- Proteins embedded in the plasma membrane identify the cell, enabling nearby cells to communicate with each other (cell recognition)
- Some proteins act as receptor molecules for interacting with specific bio chemicals (hormones, neurotransmitters and immune proteins)
- Some proteins in the cell membrane attach to cytoskeletal fibers and help to main the cell shape
- Some proteins in the membrane act as enzymes (*Eg: Microvillus on epithelial cell lining of the gut contains digestive enzymes in their cell surface membrane*)
342
What's the average diameter of a nucleus?
5 *u*m
343
By which structure the nucleus is enclosed in?
Nuclear envelope
344
Which parts does the nuclear envelope is composed of?
- Inner membrane
- Outter membrane
- Nuclear pores
345
What's te space between inner and outter membrane of the nucleus?
20 - 40 nm
346
Which structure regulates the entry and exit of substances to the nucleus?
Nuclear pores (w/ pore complex)
347
Which structure lines the interior side of the nuclear envelope?
Nuclear lamina
348
Nuclear lamina is made up of?
Protein filaments
349
**Nuclear matrix** is made up of?
Protein filaments
350
[...] and [...] are embedded throughout the nucleus
Chromatin, nucleolus
351
What's **nucleolus**?
An area of the nucleus which appears as darkly stained granules with fibers adjoining part of the chromatin
352
What's **chromatin**?
A diffused DNA and protein complex in the nuclear matrix
353
What are chromosomes?
Tightly coiled and threaded chromatins during the cell devision
354
What are the functions of the nucleus?
- Control all cell activities
- Synthesize DNA to produce new nuclei for cell devisions
- Synthesize rRNAs and ribosomal subunits required for protein synthesis (by nucleolus)
- Synthesize mRNA and tRNA according to the information present on DNA
- Store and transport of genetic information
355
What are **ribosomes**?
Subcellular components which carry out protein synthesis
356
What are the subunits of ribosomes?
- Larger subunit
- Smaller subunit
357
What are the two types of ribosomes?
- 70s and 80s
358
Where is the 70s ribosomes are located in?
- Cytoplasm of prokaryotes
- Mitochondrial matrix
- Stroma of chloroplasts
359
80s ribosomes are in which type of cells?
Eukaryotic cells
360
What are the two types of 80s ribosomes based on the nature of their presence?
- Free ribosomes
- Bound ribosomes
361
What are **free ribosomes**?
Ribosomes which are freely available in the cytoplasm
362
What are **bound ribosomes**?
Ribosomes which are attached to the membrane surface of rough ER
363
What's the function of ribosomes?
Protein synthesis
364
What's **endoplasmic reticulum**?
A network of internal membranes forming flattened or tubular sacs separating cytosol from ER lumen
365
Rough ER consists of [...] and [...] bound to surface
Flattened sacs, ribosomes
366
Where do proteins synthesized by ribosomes move in rough ER?
In to the lumen of ER
367
What are the functions of rough ER?
- Transport proteins synthesized by bound ribosomes
- Synthesizing glycoproteins
- Produce transport vesicles
- Synthesize membrane phospholipids
- Facilitate the growth of own membrane by adding phospholipids, proteins and carbohydrates
368
What's called the **membrane factory** of the cell?
Rough ER
369
What's **smooth ER**?
A network of tubular sacs without ribosomes
370
In smooth ER, membrane bound [...] are present
Enzymes
371
What are the functions of **smooth ER**?
- Synthesize lipids (Oils, steroids & phospholipids)
- Metabolism of carbs
- Produce transport vesicles to transport within cell
- Involves in detoxification
- Stores **Ca2+** ions
372
Which organelle produces transport vesicles to transport within the cell?
Smooth ER
373
Name the organelle that's involved in storing **Ca2+** ions
Smooth ER
374
Which organelle is involved in carb metabolism?
Smooth ER
375
What's **golgi apparatus**?
A stacks of flattened sacs or cisternae
376
What's the inner face of golgi apparatus?
Cis face
*Located near the ER to receive vesicles*
377
What's the outter face of golgi apparatus?
Trans face
378
Trans face of golgi apparatus give rise to [...] which bud off and travel to the other side
Secretory vesicles
379
In which type of cells golgi apparatus is abundant?
Secretory cells
380
What's are the functions of the **golgi apparatus**?
- Collecting, modifying, packaging and distribution of materials (Proteins & membrane lipids)
- Manufacturing cellulose and other non-cellular cell wall components (pectin)
- Producing lysosomes
381
Which cellular organelle produces lysosomes?
Golgi apparatus
382
What are **lysosomes**?
Single membrane bounded vesicles contributing to digestive activity
383
How do lysosomes contribute to digestive activity?
Lysosomes contain **hydrolytic enzymes** which catalyze the breakdown of carbs, proteins, lipids and nuclear acids
384
Lysosomes are capable of digesting [...]
Carbs, proteins, lipids, minerals
(All 4 types of bio-molecules)
385
What are the functions of lysosomes?
- Digest food particles received by **phagocytosis**
- Transport residue material out of by **exocytosis**
- Digest worn out organelles
- **Autolysis** causing cell death
386
Which organelle is responsible for transporting residue material out of the cell?
Lysosomes
387
What are **peroxisomes**?
Single membrane bound vesicles with oxidizing enzymes
388
Enzymes in peroxisomes catalyzes the breakdown of [...]
H2O2
389
What are the functions of peroxisomes?
- Detoxification of peroxides
- Photorespiration in plants
390
What are specialized peroxisomes which found in fat storing cells of plants?
Glyoxysomes
391
What's the the function of **glyoxysomes**?
Converting fatty acids into sugar
392
The inner membrane of mitochondria is convoluted to form [...]. It increases the surface area
Cristae
393
What are inside the mitochondrial matrix?
- 70s ribosomes
- Circular DNA
- Phosphate granules
- Enzymes
394
The mitochondrial matrix carries the enzymes for [...]
Krebs cycle (cellular respiration)
395
Cristae composed of proteins and enzymes are important for [...] and [...]
Electron transport chain, Oxidative phosphorylation
396
Whata are the functions of **mitochondria**?
- Synthesize ATP in aerobic respiration
- Involves in photorespiration
397
What's the shape of the chloroplast?
Bi-convex
398
What are **thylakoids**?
Flattened and interconnected sacs produced by a membrane system inside the chloroplast
399
By which structure the grana are interconnected?
Inter granal lamallae
400
What contains in the stroma of chloroplast?
- 70s ribosomes
- Circular DNA (chloroplast DNA)
- Many enzymes
- Starch granules and lipid droplets
401
What are the functions of the **chloroplast**?
Photosynthesis
402
What's the **cytoskeleton**?
The supporting structure of the cell and maintains it's shape
403
Cytoskeleton is made out of [...] and [...]
Microtubules, protein filaments
404
What are the three types of cytoskeletal components?
- Microtubules
- Actin filaments / Microfilaments
- Intermediate filaments
405
What's the structure of **microtubules**?
- Hollow tubes
- Wall consist of 13 columns of tubulin molecules
406
What's the protein subunit of microtubules?
Tubulin
407
What's the structure of **microfilaments**?
- Two intertwined strands of actin (each strand is a polymer if actin subunits)
408
What's the protein subunit of microfilaments?
Actin
409
What's the structure of **intermediate filaments**?
Fibrous proteins supercoiled into thicker cables
410
What are the protein subunits of intermediate filaments?
One of several different proteins depending on the cell type
*eg: Keratin*
411
What are the functions of **cytoskeleton**
- Provide strength to the cytoplasm
- Maintain the shape of the cell
- Anchorage organelles and cytosolic enzymes of the cell
- Movement of cytoplasm, cytoplasmic streaming, positioning orgenells and move chromosomes when necessary
412
Flagella are [...] structures and cilia are [...] that are often organized in [...]
Long elongated, short cellular projections, rows
413
Which component is cilia and flagella made of?
Microtubules
414
What's the structure of a cillium / flagellum?
9+2 structure
415
What's the structure (microtubule arrangement) of basal body of cillium / flagella?
9 + 0
*No center microtubules*
416
What's **9 + 2** structure?
Nine doublets of microtubules arranged in a ring, with two single microtubules in the center
417
which structure cilia and flagella bound to?
Basal body
418
What's the function of the basal body (cilia and flagella)
Anchoring cilium or flagellum to the cell
419
Cilia and flagella are covered by [...]
Plasma membrane
420
What are the functions of **cilia and flagella**?
- Acts as locomote appendages
- Can move fluid over the surface of the tissue
- Cilia lining in oviducts help move an egg towards the uterus
421
What's the structure of **centrioles**?
Centriole is made up of cylindrically arranged microtubules, which has nine sets of triplet microtubules (9 + 0). A pair of centrioles are arranged perpendicularly and are located in a region near the nucleus called centrosome.
422
Which cellular strucrure is composed of [9(x3) + 0] structure?
Centrioles
423
Centrioles are only present in [...]
Animal cells
424
Where is the perpendicularly arranged centriole pair is located?
In an area called centrosome near the nucleus
425
What's the function of **centrioles**?
- Produce aster and spindle in cell devision
426
Central vacuole is a large structure, bound by [...]
Tonoplast
427
What's the liquid inside the central vacuole is called?
Cell sap
*(differs from cytosol)*
428
What are the compounds / materials found in cell sap (inside the central vacuole)?
- Water
- Ions (Pottasium, Chloride)
- Water soluble colored pigments (anthocyanin)
429
What are the two other types of vacuoles other than the central vacuole?
- Food vacuole
- Contractile vacuole
430
What are the functions of the **vacuoles**?
- Stores water and other materials such as **sugars, ions and pigments**
- Gives turgidity and support to the cell
- Maintains water balance of the cell (osmoregulation)
- Produce colors in some plants with **sap pigments**
- Helps in digestion
431
What's **osmoregulation**?*
Osmoregulation is the process by which an organism regulates the water and electrolytic balance in its body to maintain homeostasis.
432
What's anthocyanin?*
Anthocyanins, also called anthocyans, are water-soluble vacuolar pigments that, **depending on their pH**, may appear red, purple, blue, or black.
Classification: Flavonoid, Anthocyanidin
433
Which cell types have a thin and flexible cell wall?
Prakaryotes, Fungi & some protists
434
What are the components that plant cell made of?
- Cellulose
- Hemicellulose
- Pectin
- *Lignin & suberin in some plant cells*
435
What are two types of cell walls that is generated by the plant cell?
Primary and secondary walls
436
Young cells first secrete [...], it's the wall laid down during [...]
Primary cell wall, plant cell devision
437
Which structure is outside of the primary cell wall?
Middle lamellae
438
What's pectin?*
Pectin, along with cellulose and hemicellulose, is a major component of the primary cell wall, accounting for up to 35% of primary cell walls in dicots and non-graminaceous monocots. Due to its abundance in the middle lamellae, pectin was initially considered to function primarily in intercellular adhesion
439
What are the components of middle lamallae?
Magnesium and calcium pecate
440
What's the function of middle lamella?
Gluing the adjacent cells together
441
What forms the secondary cell wall?
Deposition of hardening substances on the primary wall
442
What are the characteristics of the primary cell wall?
- Permeable
- Realtively thin
- Flexible
- Composed mainly of cellulose fibers
- Deposited on the middle lamella
443
Secondary wall lies between [...] and [...]
Primary cell wall, plasma membrane
444
In addition to cellulose, impermeable substances such as [...] and [...] are also incorporated into the secondary cell wall
Lignin, suberin
445
What's the function of lignin in the secondary cell wall?
Lignin cement anchors cellulose fibers together providing hard and rigid matrix
446
What's **plasmodesmata**?
Pits in plant cell wall through which cytoplasm of adjoing cells join
447
What are the functions of cell wall?
- Protection and support
- Allows development of turgidity when water enters the cell
- Prevents bursting due to turgidity
- Limits and controls cell growth
- Maintaining cell shape
- Hold the plant upright against the force of gravity
- Component of **appoplast pathway**
448
Appoplast pathway*
The apoplastic movement of water occurs exclusively through the intercellular spaces and the walls of the cells, depending on the water gradient.
449
What are the three type of cell junctions in animal cells?
1. Tight junctions
2. Desmosomes / Anchor junctions
3. Gap junctions / Communicating junctions
450
What's a **tight cell junction**?
Cell junction which connects the plasma membranes of adjacent cells tightly bound by specific proteins forming continuous seals around the cell
451
What's the function of **tight junction**?
Preventing leakages of extracellular fluids through intercellular space
452
Give some examples for cells with tight junctions
- Skin epithelium
- Bladder walls
- Intestines
*Epithelia in general (organ linings, skin, blood vessels)*
453
What's are **desmosomes/ anchor junctions**?
Cell junctions which mechanically attach the cytoskeleton of adjoining cells by **intermediate filaments**
454
What's the function of **desmosomes**? *(Anchor junctions)*
Desmosomes pin adjacent cells together, ensuring that cells in organs and tissues that strech, such as *skin* and *cardiac muscle*, remain connected in an unbroken sheet
455
Where can we find desmosomes?
Muscle tissue
456
What are **gap/ communicating junctions**?
Cell junctions which provide cytoplasmic channels form one cell to an adjacent cell
457
What's the function of **gap/ communicating junctions**?
Allowing signal and material exchange between adjacent cells through direct connections
458
Where can we see gap junctions?
Cardiac tissue, animal embryo
459
Which materials can be oaased through a gap junction?
Ions, sugar, amino acids
460
What's **plasmodesmata**?
Microscopic channels which runs through plant cell walls and are cytoplasmic living connections between cytoplasm of adjoining cells
461
What are the main components of ECM of animal cells?
Glycoproteins & other carbohydrates containing molecules
462
What's the most abundant glycoprotein in the animal ECM?
Collagen
*Forms strong fibers outside of the cell*
463
The collagen fibres are embedded in a network woven out of [...] secreted by cells
Proteoglycan
464
Collagen fibers are connected to the [...] of plasma membrane via fibronectin
Integrin (an integral protein that connects ECM fibers to the cell)
465
By which structure the collagen fibers in ECM are connected to the plasma membrane?
Fibronectin
466
What are the functions of **ECM** of animal cells?
- Forms a protective layer over the cell surface
- Linking ECM and cytoskeleton
- Influences the cell behavior by involving in the mechanical and chemical cell signaling
467
What's **cell cycle**?
The sequence of events that takes place in the life of a cell from end of one cell devision to the end of next cell devision
468
What's are the two major phases of eukaryotic cell cycle?
- Interphase
- Mitotic phase/ M phase
469
What's the longest phase of the cell cycle?
Interphase
*(~90% of cell cycle)*
470
What are the phases of interphase?
- G1 phase
- S phase
- G2 phase
471
What happens in **G1 phase**? (first gap phase / Growth1)
- Synthesis of proteins and production of cellular organelles leading to cell growth
- Producing proteins essential for S phase
472
What happens in **S phase**(synthetic phase)?
- DNA replication
- Synthesis of histone proteins
DNA wind around histone beads and form **chromatin**
473
What happens in **G2 phase**?
- Synthesizing essential proteins for mitotic phase
- Duplication of centrosomes
474
In which phases of mitosis are there cell cycle controlling checkpoints?
- G1 phase
- G2 phase
- M phase
475
What's the non-deviding stage of cells?
G0 Phase
476
What's the phase of cells which have exited the cell cycle?
G0 Phase
477
Most cells of the human body are in [...] phase
G0
478
What are the examples of cells in G0 phase?
Nerve cells, muscle cells
479
What are the phases of **mitotic phase / M-phase**?
- Mitosis
- Cytokinesis
*M phase covers ~10% of the cell cycle*
480
What's **mitosis**?
The nuclear division which gives rise to two genetically identical daughter nuclei from a mother nucleus
481
What's are the phases of **mitosis**?
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
Acronym : **PPMAT**
482
What happens in **prophase**?
- Chromatin fibers transformed into chromosomes
- Chromosomes appear with two sister chromatids attached at the centromere
- Nucleoli disappears
- Beginning the formation of mitotic spindle
- Centrosomes move towards the opposite poles of the cell due to the lengthening of microtubules between them
483
Chromosomal arms of sister chromatids are attached by special proteins called [...]
Cohesin
484
Spindle is formed by accumulated microtubules complex which includes [...], [...] and [...]
Centrosomes, spindle microtubules, aster (star shaped microtubules)
485
In which cells are centrosomes and centrioles absent?
Plant cells
486
Centrosomes move toward opposite poles of the cell due to?
Lengthening of microtubules between each centrosome
487
What happens in **prometaphase**?
- Nuclear envelope fragments
- Chromosomes get even more condensed
- **kinetochore** protein attaches the sister chromatids of each chromosome at their centromere
- Microtubules which are not attached with kinetochore interact with microtubules from the opposite pole
488
Which proteins are associated with centromere of chromosomes?
Cohesin (prophase) & Kinetochore (prometaphase)
489
What happens in **metaphase**?
- Centromes reach opposite poles (done)
- Chromosomes have arrived to **metaphase plate**
- At the end of metaphase, each chromosome get attached to **kinetochore microtubule** and aligned at the metaphase plate
490
What happens in **anaphase**?
- Sister chromatids are separated at the centromere
- Cell elongates as **non-kinetochore** microtubules get lengthened
- By the end of anaphase, equal and complete set of chromosomes are found at each pole of the cell
491
What happens in **telophase**?
- Nuclear envelope reforms around each set of chromosomes near the poles
- Spindle microtubules get depolymerized
- Chromosomes unwinds and become less condense to form **chromatin**
- Two genetically identical daughter nuclei are formed
492
In which phase does the division of cytoplasm occur?
At the end of telophase
(w/ a little overlap)
493
Which structure forms during the **cytokenesis** of animal cells?
Cleavage furrow
494
How do plant cells divide their cytoplasm in cytokenesis?
A cell plate form as a result of vesicles produced by **golgi apparatus**, these vesicles divide cytoplasm in to two.
495
What are the significances of **mitosis**?
1. Maintains genetic stability
2. Growth and development
3. Cell repair, replacement and regeneration
4. Asexual reproduction
496
In which phase does duplication of centrosomes takes place?
G2 phase
497
In which phase does DNA replication occur?
S phase
498
In which phase does synthesis of histone proteins takes place?
S phase
499
In which phase does DNA wind around histone beads to form chromatin?
S phase
500
In which phase does chromatin gets condensed into chromosomes?
Prophase
501
Chromosomes become visible to light microscope in [...]
Prophase
502
In which phase does nucleoli disappear and chromosomes appear with two sister chromatids attached at the centromere?
Prophase
503
What's the function of protein **cohesin**?
Attaching chromosomal arms of sister chromatids together
504
In which phase does formation of mitotic spindles begin?
Prophase
505
In which phase does nuclear envelope fragments?
Prometaphase
506
In which phase does kinetochore protein gets attached to sister chromatids of each chromosome at their centromere?
Prometaphase
507
In which phase do centrosomes reach the opposite poles?
Metaphase
508
In which phase does chromosomes arrive at metaphase plate?
Metaphase
509
In which phase does each chromosome get attached to kinetochore microtubule at their centromere and are aligned at the metaphase plate?
Metaphase
510
In which phase do sister chromatids gets separated?
Anaphase
511
In which phase does the cell lengthen as kinetochore microtubules gets shorter and non-kinetochore microtubules gets longer?
Anaphase
512
What we can see after the end of anaphase?
An equal and complete set of chromosomes at the each pole of the cell
513
In which phase does the nuclear envelope reforms?
Telophase?
514
In which phase do spindle microtubules gets depolymerized?
Telophase
515
In which phase does chromosomes unwind to become less dense and form chromatin?
Telophase
516
What we can see at the end of **telophase**?
Two genetically identical daughter nuclei
517
What the end result of mitosis?
Production of two genetically identical daughter cells
518
The cell plates which devide the plant cell in cytokenesis form as a result of [...]
Vesicles produces by golgi apparatus
