1 cell biology Flashcards
(342 cards)
1
Q
What is the function of the nucleus?
A
controls the metabolic activities of the cell as it contains genetic information in the form of DNA
2
Q
What is the nucleolus?
A
area within the nucleus that is responsible for producing ribosomes
3
Q
What is the function of mitochondria?
A
site of production of ATP in the final stages of cellular respiration
4
Q
What are vesicles?
A
membranous sacs that are used to transport materials in the cell
5
Q
What are lysosomes?
A
specialised forms of vesicles with hydrolytic enzymes that break down waste material in cells. they contain the enzyme lysozyme which breaks down the cell walls of certain bacteria.
6
Q
What is the role of the cytoskeleton?
A
controls cell movement, movement of organelles within the cell, and provides mechanical strength to the cell
7
Q
Name the three types of cytoskeletal filaments
A
microfilaments, microtubules, and intermediate fibres
8
Q
Give two types of extension that protrude from some cells
A
flagella (whip-like protrusions) and cilia (tail-like protrusions)
9
Q
What is the endoplasmic reticulum (ER)?
A
a network of membranes enclosing flattened sacs called cisternae
10
Q
What are the functions of the two types of ER?
A
smooth ER – lipid and carbohydrate synthesis, and storage
rough ER – synthesis and transport of proteins
11
Q
What is the function of the Golgi apparatus?
A
plays a part in modifying proteins and packaging them into vesicles
12
Q
what is the smooth ER function
A
lipid and carbohydrate synthesis and storage
13
Q
what is the rough ER function
A
protein synthesis and storage
14
Q
What is the formula to calculate magnification?
A
magnification = size of image/actual size of object
15
Q
why are cells stained before being viewed with a light microscope
A
staining increases contrast between different cell components, making them visible and allowing them to be identified.
16
Q
what is an eyepiece graticule
A
a glass disc that fits on top of the eyepiece lens that is marked with a fine scale from 1 to 100
17
Q
what is a stage micrometer
A
a microscope slide with a very accurate scale in micrometers engraved on it
18
Q
what is a scientific drawing
A
a labelled line drawing that is used to highlight particular features and does not include unnecessary detail or shading, it should always have a title and state the magnification
19
Q
what is magnification
A
how many times larger an image is than the actual size of the object being viewed
20
Q
what is resolution
A
the ability to see indiviual objects as separate entities
21
Q
what are living organisms composed of
A
cells (one or more)
22
Q
what are the smallest units of life
A
cells, the basic unit capable of carrying out all the functions of a living organism
23
Q
what do cells come from
A
pre-existing cells
24
Q
what is the cell theory
A
living organisms are composed of cells
cells are the smallest unit of life
cells come from pre-existing cells
25
what is striated muscle tissue composed of
repeated units called sarcomeres
26
what do sarcomeres show under a microscope
a characteristic striped (striated) pattern.
27
what is distinctive about sarcomeres and their nuclei
it challenged the idea that cells have one nucleus, as the muscle cell (fibre) has more than one nucleus per cell. it's multinucleated.
28
how long is straited muscle fibre cell
about 30mm
29
what is acetabularia
a genus of single celled green algae (gigantic)
30
how big is acetabularia
0.5 to 10 cm
31
what does acetabularia consist of
the rhizoid
the stalk
the cap
32
rhizoid of acetabularia
'small roots' at the bottom
33
the stalk of acetabualria
connects the rhizoid and cap
34
the cap of actabularia
a top umbrella made of branches that may fuse into a cap
35
what is attatched to the stalk of acetabularia
whorl of hairs that leave whorl scars
36
what notions does acetbaularia challenge
that they must be simple in structure and small in size
37
what are aseptate fungal hyphae
long threads (hyphae) with many nuclei
38
what are septa in septate fungal hyphae
dividing cell walls
39
what is the result of septate fungal hyphae
shared cytoplasm and multiple nuclei
40
what notions does aseptate fungal hyphae challenge
the idea that the cell is a single unit as the fungal hyphe have many nuclei, are very large and possess a continuous shared cytoplasm
41
how to convert from cm into mm
multiply by 10
42
how to convert from mm to micrometres
multiply by 1000
43
how to convert from micrometres to nanometres
multiply by 1000
44
unit for magnification
x the magnification
45
unit for size of drawing and actual size
whatever unit the question used or asked for
46
how to calculate magnification of an image using its scale bar
use a ruler to measure the length of the scale bar
convert this measurement to the same units as the scale bar
divide the image scale bar length by the actual image scale bar length
47
how to calculate the size of a specimen using its scale bar
measure the length of the specimen in mm
measure the length of the scale bar in mm
divide the length of specimen by length of scale bar
calcualte the size by multiplying the scale bar by the last answer. units same as scale bar
48
how to calcualte specimen size using magnification of an image
measure the length of the specimen in mm
convert the specimen length to micrometres
divide the length of the specimen by the magnification
49
metabolism is
the regular set of life supporting chemical reactions that takes place within the cells of living organisms
50
growth is
an increase in size or shape that occurs over a period of time
51
response is
a reaction (to a stimulus) by the living organism to changes in the external environment
52
homeostasis is
the maintenance of a constant internal environment by regulating internal cell conditions
53
nutrition is
the intake of nutrients, which may take different forms in different organisms. nutrition in plants involves making organic molecules (during photosynthesis) while nutrition in animals and fungi involve the absorption of organic matter
54
reproduction is
the production of offspring, either sexually or asexually, to pass on genetic information to the next generation
55
excretion is
the removal of waste products of metabolism and other unimportant materials from an organism
56
saprotrophs
excrete digestive enzymes onto food and absorb the nutrients
57
autotrophs
make their own food (like plants)
58
heterotrophs
must consumer other organisms
59
are viruses living
no they do not fulfill the functions of life
60
paramecium are
unicellular protozoa
61
what size are paramecium
0.25mm
62
where are pareamecium found
aquatic environemtns like stagnant ponds
63
how do paramecium move in all directions
using cilia
64
picture of a paramecium???
?
65
what are chlamydomonas
unicellualr green algae
66
what size is chlamyodomonas
10 to 30 micrometres
67
how do chlamyodomonas move
using flagella
68
chlamyodomonas diagram
????
69
which organisms have large SA:V
small organisms
70
which organisms have small SA:V
large organisms
71
as a cell grows, its volume increases by the power of
3 cubed
72
as a cell grows, its surface area increases by the power of
2 squared
73
if volume increases at 3 cubed and surface area increases at 2 squared, what happens to the SA:V
it decreases as the organism grows
74
what is ficks law
rate of diffusion = (concentration gradient + surface area) / distance
75
rate of diffusion =
(concentration gradient + surface area) / distance
76
why do large organisms have low metabolisms
they have small SA:V, and can hold onto heat and energy longer as they have less relative surface area
77
why do small organisms have high metabolisms
they have large SA:V and lose heat and energy very fast as they have more relative surface area
78
what part of a mammalian body is specialised to surface area
lungs, for oxygen
79
what is the genome
complete set of genes, chromosimes or genetic material present in a cell or organism, every cell except red blood cells
80
what is cellular differentiation
when an unspecialised stem cell changes and carries out a specific function in the body. cells differentiate to form different cell types due to the expression of different genes
81
according to WHAT, a complex system has properties that its constituent parts do not have. the whole is more than the sum of its parts
emergent properties
82
how many genes does the human genome have
21,000
83
totipotent
Can differentiate into any type of cell including placental cells.
Can give rise to a complete organism.
84
pluripotent
Can differentiate into all body cells, but cannot give rise to a whole organism.
85
multipotent
Can differentiate into a few closely related types of body cell.
86
unipotent
Can only differentiate into their associated cell type. For example, liver stem cells can only make liver cells.
87
when are totipotent stem cells found
basicallynone after birth
88
when are pluripotent stem cells found
very few in adults
89
what can multipotent stem cells do
become any cell in e.g. circulatory system
90
what can unipotnet stem cells do
become any cell in e.g. a heart
91
what is stargardts disease
an inherited from of juvenile macular degeneration, that causes progressive loss of centrl vision
92
when is stargardts disease
late childhood to early adulthood
93
what is stargardts disease caused by
a recessive genetic mutation in gene ABCA4, which causes an active transport protein on photoreceptor cells to malfunction. this ultimately causes photoreceptor cells to degenrate
94
how does stem cell therapy help stargardts disease
patients are given retinal cells derived from human embryonic stem cells which are injected into the retina. the inserted cells attach to the retina and become functional
95
stem cells in leukemia
harvesting hematopoietic stem cells (HSC's) which are multipotent stem cells. they can be taken from bone marrow, perioheral blood or umbilical cord blood. the HSC may come from either the patient or from a suitable doner. the patient then undergoes chemotherapy and radiotherapy to get rid of the diseased white blood cells. the next step involves transplanting HSC's back into bone marrow, where they differentiate to form new healthy white blood cells.
96
arguments for stem cells
cell therapy to eliminate serious diseases or disabilites
transplants can be easily obtained without requiring the death of another human or inflicting any kind of pressure on normal body which happens when someone donates an organ
the stem cells are harvested from the embryo at an early stage when the embryo has not yet developed a nervous system and thus it is not likely to feel any pain
97
how are embryo stem cell cultures harvested
removal of nucleus from donor egg cell
nuclear transfer of host dna from somatic cells
4 cell stage
morula
blastocyst
embryo stem cell culture containing transferred dna from host somatic cells
98
how are stem cells obtained from bone marrow
blood is taken and stem cells are seperated out
99
how are egg cells obtained
a woman takes fertility drugs and then an ultrasound guided needle is inserted.
100
why are adult stem cells less valued
because they have a narrower range of cells they can divide into
101
arguments for stem cell research (drug research)
more accurate than animals
GM foods
systemic toxication of drugs
102
arguments for stem cell research (developing science)
could be used in producing regenerated tissue for burns
replacement organs
(therapeutic)
103
what is stargardts macular dystrophy
a recessive mutation of ABCA4 which causes the retina cells to malfunction and photoreceptive cells to degenerate. this can lead to poor vision or severe loss of vision (blindness)
104
how are stem cells used in leukemia
stem cells are removed from bone marrow and frozen.
chemotherapy and radiotherapy is given to stop the body being able to make blood cells. then the stem cells are reinjected.
105
differences in eukaryotic and prokaryotic cells
Eukaryotic cells have a separate membrane-enclosed nucleus, whereas the DNA of prokaryotes is freely floating in the cytoplasm.
Eukaryotic cells have a complex system of membrane-bound organelles that divides the cell into numerous enclosed regions – known as compartmentalisation.
Prokaryotes do not have any membrane-bound organelles.
106
what do prokaryotes not have any of
membrane bound organelles
107
pili function
protein filaments on the cell wall that help in cell adhesion and in transferring of DNA between two cells
108
70S ribosomes
are the site of protein synthesis
109
plasmids
small circles of DNA that carry a few genes, often these give the cell antibiotic resistance and are used in creating genetically modified bacteria
110
difference in ribosome size between prokarytic and eukarytoic cells
ribosomes in prokaryotic cells (70S) are smaller than ribosomes found in eukaryotic cells (80S).
111
what do 70S and 80S refer to
sedimentation rate of RNA subunits
112
steps of binary fission in prokaryotes
The chromosome is replicated semi-conservatively, beginning at the point of origin (shown in red in Figure 2).
Beginning with the point of origin, the two copies of DNA move to opposite ends of the cell.
The cell elongates (grows longer).
The plasma membrane grows inward and pinches off to form two separate, genetically identical cells.
113
how are mitochondria insides sealed from the rest of the cell
mitochondrial envelope
114
advantages of eukaryotic cells being compartilised
Greater efficiency of metabolism as enzymes and substrates are enclosed, and therefore much more concentrated, in the particular organelles responsible for specific functions.
Internal conditions such as pH can be differentiated in a cell to maintain the optimal conditions for different enzymes.
Isolation of toxic or damaging substances away from the cytoplasm, such as the storage of hydrolytic enzymes in lysosomes.
Flexibility of changing the numbers and position of organelles within the cell based on the cell’s requirements.
115
where is dna replicated
in the nucleus
116
how do you distinguish the golgi apparatus
it is not found near the nucleus
the lines are unattached to eachother
it has no ribosomes attatched
117
what is exocytosis
where things leave the cell through the plasma membrane
118
what is endocytosis
where things enter the cell through the cell membrane
119
what does the vacuole do
store liquid and sap which pushes the organelles against the plasma membrane. therefore the plasma membrane must be strong
120
what is transcription
copying the dna by synthesising messenger RNA (mRNA) from the DNA base sequences
121
what is translation
interpreting the genetic code to synthesise proteins (more specifically polypeptide chains) on ribosomes
122
microscope resolution def
the shortest distance between two seperate points in a microscopes field of view that can still be distinguished as distinct objects
123
do electron microscopes have a higher or lower resolution than light microscopes
much higher
124
what is the difference in resolution between an electron and light microscope
a light microscope is 200nm compared to 0.1nm
125
the ??? the value, the lower the resolution
higher
126
how many times can an electron microscope magnify objects by
500,000
127
how many times can a light mcirosocope magnify by
2000
128
compartmentalisation def
the formation of compartments within the cell by membrane bound organelles
129
which cells are compartmentalised
all eukaryotes where membranes are used to isolate certain parts of the cell from the rest to form separate organelles.
130
advantages of being compartmentalised
- greater effiency of metabolism as enzymes and substrates are enclosed, and therefore more concentrated for their functions
- internal conditions such as pH can be differentiated in a cell to maintain the optimal conditions for different enzymes
- isolation of toxic or damagin substances away from cytoplasm (like lysozyme)
- flexibility of changing numbers and posisitions
131
how do prokaryotes reproduce
binary fission
132
how does binary fission work
- chromosome replicated semi conservatively, beginning at point of origin
- beginning there, the two copies of dna move to opposite ends of the cell
- the cell elongates
- the plasma membrane grows inward and pinches off to form two seperate genetically identical cells.
133
what causes the fluidity of the membrane
phopholipids, which have the ability to move with respect to each other in the same plane. cholesterol also helps
134
benefits of membrane fludiity
the cell can perfom processes such as endocytosis nad exocytosis
135
describe the fluid mosiac model,
phospholipid bilayers with proteins embedded in the bilayer, making the membrane look like a mosaic.
136
phosphate heads are hydro...
hydrophilic (love water)
137
what is a phospholiid
One type of lipid, called triglycerides, are made up of one glycerol and three fatty acid molecules.
a phospholipid is a lipid where one of the fatty acids has been replaced by a phosphate group
138
fatty acids are hydro...
phobic
139
what is an amphipathic molecule
A molecule that has both a hydrophilic and a hydrophobic part
140
integral proteins are
amphipathic (they have hydrophobic and hydrophilic properties) and are embedded in the plasma membrane. In most cases, they pass completely through the membrane.
141
peripheral proteins are
polar (hydrophilic) and are attached to the outside of the plasma membrane.
142
channels in proteins
some proteins have a pore/channel that allows the passive transport (no energy required) of substances between the inside and outside of the cell.
143
carriers in proteins
these proteins bind to substances on one side of the membrane and then change shape to transport them to the other side. Carrier proteins that use energy to change shape are termed protein pumps.
144
recognition in proteins
certain proteins help the cell in differentiating between self and non-self cells (important in triggering an immune response).
145
receptors in proteins
these proteins usually span the whole membrane to relay information from the inside or outside of the cell.
146
enzymes in proteins
these are proteins that enhance the rate of reactions that happen at the membrane level.
147
glycolipids are
a phospholipid and a carbohydrate attached together.
148
cholesterol is
a sterioid and is found only in animal cell membranes.
149
cholesterol is vital in
helping to maintain the structure of the cell membrane
150
glcolipids are important in
maintaining the structure of the cell membrane and in cells differentiating between self and non-self cells.
151
what to remember when drawing the fluid mosiac model
Individual phospholipid molecules are shown by using the symbol of a circle with two parallel lines attached.
A range of membrane proteins is shown, including peripheral and integral.
The following labels are included: phospholipid bilayer, phospholipid molecule, glycoprotein, glycolipid, integral and peripheral proteins and cholesterol.
152
what is cholesterol
is a steroid made up of a non-polar part comprising four ring structures, a hydrocarbon tail, and a polar hydroxyl group
153
cholesterol is amphipathic. this means it can
insert itself into cell membranes by interacting with the phospholipids (which are also amphipathic).
154
choleserol in membranes restricts what
the movement of phopholipids and other molecules, reducing molecule fluidity.
also restricts membrane permeability to hydrophilic molecules and ions like sodium and hydrogen.
155
what does cholesterol do at low temps
disrupts the regular packing of the hydrocarbon tails of phospholipid molecules, which prevents the solidification of the membrane. This enables the membrane to stay more fluid at lower temperatures, allowing the membrane to function properly.
156
Davson-Danielli
MODEL
157
what does simple diffusion require
a gas/liquid medium
concentration gradient from high to low
living and non-living organism
158
what does faciliated diffusion require
specific channel or carrier proteins that vary depends on size or shape of entering molecule
159
what does diffusion depend on or is effected by
temperature
surface area of membrane
size of particles
concentration gradient of diffusing particles
160
what does active transport require
ATP
| low to high concentraiton gradient
161
endocytosis is
molecules in
162
phagocytosis is
cell eating
163
pinocytosis is
cell drinking
164
what subsections of endoyctosis are there
phagocytosis
| pinocytosis
165
what is exocytosis
molecules out
166
what is excretion of exoyctosis
undigested remains
167
what is secretion of exocytosis
releasing enzymes from inside secretary vesicles attatched to inside plasma membrane wall
168
give substnces to be transported
small non polar molecules
small ions
larger molecules
very large molecules
169
example of small non polar molecules for transportation
oxygen or carbon dioxide
170
example of small ions to be transported
Na+ or Ca2+ or K+
171
example of larger molecules to be transported
glucose, nitrates
172
example of very large molecules to be transported
proteins
173
problems that may occur in transportation
very small molecules move super quick through p.b.
polar molecules cant get past the fatty acid tails of p.b.
larger molecules cant cross p.b. and sometimes have to go against conc grad
very large protein molecules cant cross membrane at all even using integral proteins.
174
integral proteins
triangular soft lump
175
transport proteins
like a chromosome
176
periphal protein
oval lump on inside end of hydrophilic head
177
channel protein
cylindrical shape going through p.b.
178
what is a triglyceride
a glycrol and three fatty acids
179
what is a phospholipid
a glycerol, two fatty acids and a phosphate gorup
180
what does cholesterol control
membrane fluidity and permeability
181
what is the ratio of total lipid surface area to total cell membrane surface area
2:1
182
how did pasteur disprove the cell theory
Pasteur boiled nutrient broth in three swan-neck flasks. He then broke the neck of one flask to allow air to enter, but left the other flask unbroken. The broth in the flask where the swan neck was not broken remained clear (as no microbes were formed and any microbes from the air were trapped in the curve of the swan neck), while the broth in the broken-necked flask became cloudy, as microbes carried to the flask in the air grew and multiplied. In the third flask, Pasteur tilted the flask to expose the broth to the microbes in the curve of the swan neck. Pasteur’s experiment proved that spontaneous generation of cells and organisms does not occur on Earth, showing that the present conditions (temperature, pressure, light, radiation level and so on) do not sustain the process.
183
what was the miller - urey experiment
Miller and Urey recreated the conditions of early Earth in a closed system by including a reducing atmosphere (low oxygen) with high radiation levels, high temperatures and electrical storms. After running the experiment for a week, some simple amino acids and complex oily hydrocarbons were found in the reaction mixture. This experiment proved that non-living synthesis of simple organic molecules was possible.
184
whcih part of the cell theory did louis pasteur disprve
spontaneous generation
185
which part of the cell theory did miler-urey disprove
that the first cell came from non living materiak
186
what conditions are required for life to emerge and persist
1. Simple organic molecules, such as amino acids, fatty acids and carbohydrates, must be formed.
2. Larger organic molecules, such as phospholipids, RNA and DNA, must be assembled from simpler molecules.
3. Organisms reproduce, so replication of nucleic acids must be possible.
4. Biochemical reactions require set conditions, such as pH. Therefore, self-contained structures, such as membranes, are necessary.
187
what does the endosymbiotic theory explain
the origin of eukaryotic cells
188
what is the endosymbiotic theory
This theory supports the idea that mitochondria and chloroplasts were themselves prokaryotes that were taken in by larger prokaryotes by endocytosis.
Instead of being digested and broken down, these cells remained inside the host cells.
Cells that could carry out aerobic respiration and hence provide energy to their host cell (which were probably anaerobes who did not need oxygen) evolved into mitochondria.
Prokaryotic cells that could convert light energy to chemical energy (probably cyanobacteria) became chloroplasts and passed on sugars produced during photosynthesis to the host cell.
189
what do both mitochondria and chloroplasts have
Have double membranes, as expected for cells taken in by endocytosis.
Have circular naked DNA, as in prokaryotes.
DNA is formed as single chromosomes.
Have 70S ribosomes, as in prokaryotes.
Divide by binary fission like prokaryotic cells.
Are susceptible to some antibiotics.
190
what is mitosis used for
to produce new cells for growth and repair
191
what is meiosis used for
the formation of gametes only
192
how do bacteria reproduce
asexually by binary fission (NOT meiosis or mitosis)
193
how do yeasts reproduce
asexually by budding (NOT meiosis or mitosis)
194
interphase
period of cell growth
cell prepares cell for cell division (mitosis)
genetic material/dna is copied and checked for errors - prevents mutations being passed on
new organelles and proteins are made
195
mitosis
process by which a nucelus divides into two - each with an identical set of chromosomes - the nuclei are genetically identical
196
what are the four phases of mitosis
```
prophase
metaphase
anaphase
telophase
(followed by cytokeneisis)
```
197
what is cytokeneisis
division of the cells into two genetically identical daughter cells.
198
G1 - the longest phase
protein synthesis - cell "grows"
most organelles produced
volume of cytoplasm increases
cell differentiation (switiching on or off genes)
if cell is not going to divide it stays in this phase
199
S - replication phase
DNA replication - this must occur if mitosis is to take place. the cell enters this phase only if cell division is to follow.
200
G2 - second growth phase, short
short gap before mitosis (cell division)
cytoskeleton of cell breaks down and the protein microtubule components begin to reassemble into spindle fibres - required for cell division
201
when does mitosis occur
when an increase in number of cells is needed
202
what are cancers caused by
uncontrolled cell division by mitosis
203
what does a centromere do
hold 2 chromatids together
204
what is a gene
a segment of DNA that codes for a trait
205
chromatids are identical...
copies
206
a chromosome is essentially made up of
2 sister chromatids
207
how many pairs of chromosomes do we have
23 pairs, 46 chromosomes
208
what does each pair of chromosomes contian
one chromosome from the father and one from the mother
209
each indiviual pair of similar chromosomes is called
a homologous pair.
210
where does mitosis take place?
replacement of cells (e.g. red blood cells, epidermal cells)
growth of tissues by producing new extra cells
divison of zygote into multicellular organism
formation of clones of T and B lymphocytes and plasma cells in the immune response
asexual reproduction
the production of genetically identical cells in multicellular organisms (allowing certain cells to retain the ability to develop into any other type if needed as a result of damage. )
211
before a cell, it goes through interphase, where
its chromosomes are copied exactly, (replication), ATP is synthesised - provides energy for cell division; organelles are replicated and proteins are made.
212
during prophase...
DNA of each chromosome is copied to form two chromatids (sister chromatids).
chromatids condense
nuclear envelope breaks down
chromosomes lie freely in the cytoplasm
centrioles move to opposite ends of the cell, forming protein spindle fibres which extend to the equator of the cell.
213
during metaphase...
chromosomes line up at the equator, the spindle fibres from each pole become attached to the centromere of the chromosomes.
214
during anaphase...
spindle fibres contract
centromeres are split and pairs of sister chromatids are seperated and dragged to opposite poles assuming a V shape, the centromeres lead.
a complete set of chromosomes is therefore found at each pole. ATP is required.
215
during telophase...
chromatids reach their respective poles and uncoil - become thin and long and called chromosomes again.
spindle fibres break down
nuclear envelope forms around each group of chromosomes, forming two nuclei
cytokinesis follows, cytoplasm divides and a plasma membrane forms two indiviual cells; cell enters interphase once again.
216
aside from pasteur, what other evidence is there that cells only come from pre-existing cells
a cell is a highly complex structure and no natural mechanism has been suggested for producing cells from simpler subunits
no example is known of increases in the number of cells in a population, organism or tissue without cell division occurring
viruses are produced from simpler subunits but they do not consist of cells, and they can only be produced inside the host cells that they have infected.
217
what is mitosis
the division of the nucleus into two genetically identical daughter nuclei
218
mitotic index =
number of cells in mitosis
---------------------------------------
total number of cells
219
what is cytokinesis
the actual physical process of cell division
220
cytokenesis in animal cells
the plasma membrane is pulled inwards around the equator of the cell to form a cleavage furrow.
this is done by a ring of contractile protein immediately inside the plasma membrane at the equator. the proteins are actin and myosin and are similar to the proteins that cause contrction in muscle. when the cleavage furrow reaches the centre, the cell is pinched apart into two daughter cells.
221
cytokenesis in plant cells
the vesicles are moved to the equator where they fuse to from tubular structures across it.
with the fusion of more vesicles these tubular structures merge to form two layers of membrane across the whole of the equator, which develop into the plasma membranes of the daughter cells and are connected to the existing plasma membranes at the sides of the cell, completing division of the cytoplasm.
222
what do cyclins do
ensure that everything is happening at the right time
223
what do cyclins bind to
enzymes called cyclin dependent kinases.
224
when cyclins have binded to the kinases what happens
thekinases become active and attach phosphate groups to other proteins in the cell. the attatchement of phosphate riggers the other proteins to become active and carry out tasks specific to one of the phases in the cell cycle.
225
what are the four main types of cyclin in human cells
D
E
A
B
226
what does cyclin D do
triggers cells to move from G0 to G1 and from G1 to S
227
what does cyclin E do
prepares the cell for DNA replication in the S phase
228
what does cyclin A do
activate DNA replication inside the nucleus in the S phase
229
what does cyclin B do
promote the assembly of the mitotic spindle and other tasks in the cytoplasm to prepare for mitosis.
230
what is a mutation
a change in an organism's genetic code. a change in the base sequence of a certain gene can result in tumour formation. however, some parts of a gene do not code for anything so a mutation in these areas will not affect the organism. so not all gene mutations lead to uncontrolled cell division.
231
what are mutagens
the agents that cause gene mutations. although not all mutations result in cancers, anything that causes a mutation has the potential to cause a cancer.
232
what can mutagens be
chemicals referred to as carcinogens, such as asbestos or dioxin.
high energy radiation like x rays
short wave UV light
viruses like hepatitis B
233
what are oncogenes
a mutated gene that contributes to the development of a tumour. in their normal, un-mutated state, oncogenes are called proto-oncogenes, and they help in the regulation of cell division
234
once abnormal cell division has started at a particular place in the body,
a malignant primary tumour begins to form. if left untreated, this may follow a particualr development pathway to form secondary tumours.
235
what is metastatis
when a primary tumours follow a particular development pathway to form secondary tumours.
236
metastatis steps
cancerous cells detatch from the primary tumour
some cancerous cells gain the ability to penetrate the walls of lymph or blood vessels and so circulate around the body.
the circulatin cancerous cells invade tissues at different locations and develop, by uncontrolled cell division, into secondary tumours.
237
metastasis definition
movement of cells from a primary tumour to other parts of the body where they develop into secondary tumours.
238
in which place in the cell cycle do mutations happen
S-synthesis
239
inwhich place in the cell cycle do genes become modified to an oncogene
G2 primaryily
240
what are cyclins
a group of proteins whose function is to regualte the progression of a cell through the cell cycle.
241
what do two strands of RNA form
DNA
242
what to nucleotides join together ot form
a single stranded nucleic acid (RNA)
243
each nucleotide is made up of how many parts
3
244
what are nucleotides made up of
carbon, hydrogen , oxygen, nitrogen and phosphorus.
245
when is a phospholipid formed
when a phosphate group replaces one of the fatty acids. these are vital to forming cell membranes
246
what affects the physical proprties of the tri-glyceride
the length, and whether the fatty acids have double or single carbon bonds
247
what is a triglyceride
3 fatty acids and 1 glycerol
248
what is a fatty acid
a chain of carbons and hydrogens with a carboxylic acid group. the length of the chain can vary from 4 - 28 carbons
249
what is simple diffusion
passive movement of molecules/ions along a conc grad
250
what is facilitated diffusion
facilitated diffusion is passive movement of molecules/ions along a conc grad through a protein channel without use of energy
251
what is osmosis
net movement of water across a partially permeable membrane from a region of high conc to low conc
252
what is active transport
the movement of molecules/ions against the conc grad with the use of ATP
253
what is endocytoisis
the infolding of the membrane/formation of vesicles to bring molecules into the cell with use of energy
254
what is exocytosis
the infolding of the membrane of vesicles to bring molecules from the cell with use of energy
255
what does cytokinesis involve
It involves the formation of a cell plate in plant cells only.
256
Cholesterol has a role in making sure which type of protein is anchored to the membrane?
peripheral
257
what does "The oldest fossilised cells resemble prokaryotes." suggest
the idea that prokaryotes evolved before eukaryotes
258
State the name of the molecule that CDKs attach to proteins in order to activate them.
phosphate group, prompting proteins to carry out their specific fucntion
259
example of a therapuritc use of a stem cell
restoration of myocardial tissue
260
how large are bacterium
around 1 micrometer
261
how large are plant and animal cells
around 100 micrometers
262
how large are viruses
100nm
263
when does cytokenesis occur
after nuclear division in mitosis
264
what do prokaryotes not have
golgi apparatuses or nuclear membranes
265
The smooth endoplasmic reticulum is responsible for the synthesis and storage of
lipids
| and steroids
266
Cholesterol is made up of a nonpolar part composed of four ring structures, a hydrocarbon tail and which of the following groups?
polar hydroxyl group
267
Recognition proteins are able to differentiate between substances. This is useful and helps them to trigger which type of response?
immune
268
Which cell structure, important in endocytosis and exocytosis, promotes the movement of materials within a cell? (Answer with one word)
vesicles
| cytoskeleton
269
how are cyclins activated
by the phosphorylation by a CDK-activating kinase (CAK).
270
what does cholersterol do within the plasma membrane
reduce membrane fluidity at high temps
271
why is it beneficial that cholesterol is amphipathic
its attracted to both polar and non polar molecules, so can interact with polar phosphate heads and the non polar fatty acid tails. buffer of membrane fluidity, so that the fluidity is always at a good level for the cells
272
at low temps, the phospholipids in the membrane do not have enough energy to move around...
vigorously, so clump together, meaning that the membrane fludiity is too low. cholesterol can interact with the fatty acid tails, dispersing them so that they can't clump together. This increases the membrane fluidity
273
At high temperatures, the phospholipids in the membrane have too much energy and move around too much which...
increases the fluidity of the membrane to the point where it becomes leaky. This is bad as the role of the membrane is to control very tightly what substances can enter and exit the cell. In this scenario, cholesterol interacts with the phosphate heads, pulling them together so that they don't move around as much as the fluidity is reduced to a good level.
274
A cell that is dividing too rapidly may have lost its ability to enter which part of the cell cycle
G1
275
what were pasteur's swan necked flasks filled with
nutrient broth and then sealed. some flasks were boiled to kill living organisms inside them. no microorganisms developed. spon. gen. rejected
276
do ribsomes have membranes
no
277
The Miller-Urey experiment was able to produce some simple organic molecules. Complex oily hydrocarbons were synthesised, as well as which other type of simple compound?
amino acids
278
DNA is loosely packaged by histones to form which molecule? (Give your answer with one word)
chromatin/nucleosomes
279
which cyclin triggers the start of mitsois
cyclin b
280
Biologists suspect that endosymbiosis gave rise to mitochondria before chloroplasts because:
All eukaryotes have mitochondria, whereas many eukaryotes do not have chloroplasts.
281
Some membrane-spanning proteins are able to change shape to allow materials to cross the cell membrane. Name the type of integral membrane protein that has this function.
protein pump
282
The Miller-Urey experiment attempted to recreate the early atmosphere of a younger Earth. Which of the following best describes the early atmospheric conditions?
low oxygen atmosphere
high radiation levels
high temperatures
electrical storms
283
how thick is a plasma membrane
10 nm
284
function of prokaryotic cell walls
prevent cell bursting in hypotonic solutions.
| maintain cell shape under various conditions.
285
factors contributing to the development of malignant tumours
mutagens such as short-wave UV, mutations in oncogenes and ability to form secondary tumours
286
is infrared light a mutagen
no
287
somatic cell nuclear transfre
AEBE
adult somatic cells
enucleated egg ccell
blastula
embryonic stem cells
288
nuclear reprogramming
RAI
reprogramming factors
adult somatic cells
induced pluripotenti cells
289
evidence for davson danelli model
phospholipids
sa was twice sa of a red blood cell
proteins
protein coat to explain the differential permeability of the plasma membrane
implied fixed positions
electron mirographs
plasma appeared as two dark bands on the outside with alight band in between
290
what falsified the davson danelli model
freeze fracture electron micrographs
showed globular proteins present don't eh upper surface of the inner phospholipid layer
proteins had hydrophobic parts nad varied in size. suggested they were embedded within the bilayer and hydrogphoic regions could attract the fatty acid tails
x ray diffraction
at higher temps the membrane behaved as a liquid
membrane proteins of two cells linked to two florescent labels.
two cells fused. after a short time they were fully mixed. proved that tprotiens were free to move within the membrane
291
tranpsort proteins
channels to allow susbtanes to passively move through the membrane
pumps for active transport
292
glycoproteins
cell to cell communication
recet=ptors for chemical signals such as hormones.
cell to cell recognition
antigens
cell adhesion
binding cells together
293
is chcholesterol amphipathic
yes
294
what is the phospholipid bilayer permeable to
water
co2
o2
fatty acids
urea
295
what is the phospholipid bilayer impermeable to
amino acids
glucose
hydrogen ions
chloride ions
296
hat are channel protein specific for
a single substance
297
What is the main role of ATP in the action of a Sodium-Potassium pump?
donates a phosphate to the grouo
298
Lysosomes are often absent from plant cells and so a different organelle will take on the role of the lysosome. State the name of the plant cell organelle that is capable of doing this role.
vacuole
299
what controls shape change in sodium potassium pumps
ion conentration, phosphate release
300
State the name of the molecule that CDKs attach to proteins in order to activate them.
phopshates
301
state the name of the eukaryotic organelle that helps to establish microtubules during cell division
centrioles
302
state the name of the eukaryotic organelle that helps to establish microtubules during cell division
centrioles
303
Biologists suspect that endosymbiosis gave rise to mitochondria before chloroplasts because:
all eukaryotes have mitochndria whereas many eukaryotes dont have chloroplasts
304
In a cell, the following reaction takes place: glucose → ethanol + carbon dioxide. The reaction yields a small amount of ATP. This reaction can take place in:
I: A yeast cell
II: A plant cell
III: A human cell
I and II
305
how does active transport across sodium potassium pumps be summarised
When the pump is open to the inside of the axon, three sodium ions (Na+) enter the pump and attach to their binding sites.
ATP donates a phosphate group to the pump.
The previous stage causes the protein to change shape expelling Na+ to the outside.
Two potassium ions (K+) from outside then enter and attach to their binding sites.
The binding of the K+ leads to the release of the phosphate which causes the pump to change shape again so that it is only open to the inside of the axon.
K+ is released inside.
Na+ can now enter and bind to the pump again.
306
purpose of pcr
amplify small fragments of dna
307
PCR
Denaturation – DNA sample is heated (~90ºC) to separate the two strands
Annealing – Sample is cooled (~55ºC) to allow primers to anneal (primers designate sequence to be copied)
Elongation – Sample is heated to the optimal temperature for a heat-tolerant polymerase (Taq) to function (~75ºC)
308
what does taq polymearse actually do
extend the nucleotide chain from the primers - therefore primers are used to select the sequence to be copied.
309
purpose of gel electrophoresis
used to separate and isolate proteins or dna fragments based on mass/size
310
how is dna cut in half
by restriction endonuclease
311
why do fragments seperate in dna seperation
because dna is negatively charged due to the presence of a phosphate group on each nucleotide.
312
protein seperation in gel elctrophoresis
Proteins may be folded into a variety of shapes (affecting size) and have positive and negative regions (no clear charge)
Proteins must first be treated with an anionic detergent (SDS) in order to linearise and impart a uniform negative charge
Protein samples are placed into a polyacrylamide gel and sizes compared against known industry standards
Separated proteins are transferred to a membrane and then target proteins are identified by staining with specific monoclonal antibodies (Western blotting)
313
gene modification by gene transfer:
isolate the desired gene from the original species using restriction endonucleases
isolate an appropriate plasmid (small loop of DNA containing a few genes that is often traded between bacteria)
Cut the plasmid with the same restriction endonuclease that was used to remove the desired gene. This will open the loop of the plasmid, forming a string with two ends.
Mix many copies of the target gene and cut plasmid together to allow their complementary unpaired sequences to join together, thus adding the gene into the plasmid.
Use the enzyme DNA ligase to covalently bond the DNA backbones of the gene and plasmid together, permanently sealing the gene into the plasmid loop.
Transfer the plasmid with the target DNA (called a recombinant plasmid) back into the bacterium.
Grow colonies of the genetically modified bacteria that now produce a eukaryotic protein.
314
what is different with gene transfer of eukaryotic cells
If the gene is eukaryotic, use reverse transcriptase to produce an edited version of the gene. Although the genetic code is universal, eukaryotes delete parts of the RNA before it leaves the nucleus to be translated. Bacteria have no nucleus and cannot perform this step, so scientists compensate by making DNA without the parts that should be deleted.
315
what are the consequences of sticky ends
Most restriction endonucleases leave ‘sticky ends’ where one half of the helix extends beyond the other, leaving a few unpaired bases. Using the same restriction endonuclease gives the gene and the plasmid complementary unpaired sequences that ‘stick’ together by hydrogen bonding.
Alternatively, use a restriction endonuclease that produces blunt ends for both gene and plasmid. Then add a series of guanine nucleotides to the 5’ ends of the gene, and cytosine nucleotides to the 5’ ends of the plasmid. This creates complementary sequences that will allow them to stick together.
316
what is cdna
complementary dna
317
plants methods of cloning
runners
bulbs
tubers
318
fungus method of cloning
budding
319
animals method of cloning
budding
parthenogenesis
320
scientific methods of cloning
Splitting or fragmentation of an embryo to clone an animal before the cells have differentiated.
Using differentiated cells and somatic cell nuclear transfer to clone adult animals.
321
Using differentiated cells and somatic cell nuclear transfer to clone adult animals.
Donor somatic (body) cells are taken from the organism that will be cloned and cultured in the lab.
Somatic cells with the least DNA inactivation should be chosen. In this case, cells were taken from the udder of the donor sheep.
The cell is starved so that the amount of cellular material other than the nucleus is reduced.
An unfertilised egg is taken from another individual.
The unfertilised egg is enucleated (the nucleus is removed).
In this case, the nucleus was removed using a tiny pipette.
The enucleated egg is fused with a donor cell.
In this case, the cells were placed next to each other and an electrical current was used to disrupt the cell membranes enough so that they would fuse together.
The fused cell is allowed to divide until a small embryo has formed.
The embryo is transplanted into the uterus of a surrogate mother.
The pregnancy and birth of the offspring proceed normally.
322
what is methane
is a carbon molecule which is produced in anoxic conditions and can oxidise into carbon dioxide and water.
323
methanogenic archeans
bacteria that are found in several anoxic environments and produce methane as part of the carbon cycle.
324
ruminants
mammals that have a mutualistic relationship with methanogenic archaeans that help them to digest cellulose from the cell walls in the plants they eat. This creates methane, which is released as gas from the mammal.
325
graph representing the change in cell sa to vol ration with increaseing cell diameter
curve with point close to x
326
as size increases
sa:vol decreases
327
what do phagocytic and whit eblood cells and photosyntheitcic baterium have
70s ribsomes
328
is evaporation of water from sweat on the skin surface osmosis
no
329
two sugar monomers make
a disaccharide
330
waht makes up a digyceride
a glyceride consisting of two fatty acid chains covalently bonded to a glycerol molecule through ester linkages.
331
spec heat cpaacity of methane
2.2
332
latent heat of vap of methane
760
333
bp of methane
-160
334
what is common to rna and dna
nitrogenous bases
335
which organisms produce methane in anaerobic environments such as waterlogged soils
archea
336
HIv leads to
a reduction in the production of antibodies
337
what is produced by type II pneumocytes
pilmonary surfactant
338
how do neonictinoid pesiticdes caues paralysis and death of honeybees
bind to neurotransmitter receptors
339
what contribution did the x ray diffraction conducted by rosaling franklin make to our understanding of dna
indicated the helical shape of themolecuel
340
all flowering plants depend on the ...
duration fo periods of light and darkness to regualte the timing of reproduction
341
effect of disruptive selection
favours indiviuals with intermediate forms of a characteristiic
342
waht do the intercostal muscles do during exhalaation
external intercostal muscles contract and internal intercostal muscles relax
