IMMS (summary Sheets) Flashcards
(238 cards)
1
Q
What is the structure of DNA?
A
- Double helix
- Complimentary base pairs (A - T & G - C)
- Coils around nucleosomes —> supercoils —> chromosomes
2
Q
What is a autosome?
A
Any chromosome which isn’t sex determining
3
Q
How many pairs of chromosomes are there in humans?
A
22 pairs of autosomes & a pair of sex chromosomes
4
Q
What are the sex chromosomes in males and females?
A
XY - males
XX - female
5
Q
Define karyotype
A
Number and appearance of chromosomes in a cell
6
Q
What does each chromosome contain?
A
A continuous DNA duplex of 10^7 base pairs and contains several hundred genes
7
Q
How many genes does each individual have?
A
30,000
8
Q
What is the structure of a chromosome?
A
Has a long arm (q) and a short arm (p) separated by a centromere
9
Q
What is the purpose of mitosis?
A
To produce 2 daughter cells, genetically identical to parent cells
10
Q
What is mitosis used for?
A
Growth and to replace dead cells
11
Q
What is the DNA structure called when not in replication?
A
Chromatin
12
Q
What is the DNA structure called when in replication?
A
Chromosomes
13
Q
What is the DNA structure called when after replication?
A
Chromatids
14
Q
What must happen for mitosis to occur?
A
The cell must be in cell cycle - interphase
15
Q
What is the longest phase of mitosis?
A
Interphase
16
Q
What happens in G1 of interphase?
A
- No visible activity
- Rapid growth
- Normal metabolic function
- New organelles produced
- Protein synthesis of proteins involved in spindle formation
17
Q
What happens in S (synthesis) of interphase?
A
- DNA doubles through DNA replication
- Histone proteins double through protein synthesis (2x as much DNA at end of S)
- Centrosome replication
18
Q
What happens in G2 of interphase?
A
- Chromosomes condense (coil up and become visible)
- Energy stores accumulate
- Mitochondria and centrioles double
19
Q
What happens in prophase in mitosis?
A
- Chromatin condenses into chromosomes
- Centrosomes nucleate microtubules and move to opposite poles of nucleus
20
Q
What happens in prometaphase in mitosis?
A
- Nuclear membrane breaks down
- Microtubules invade nuclear space
- Chromatids attach to microtubules
- Cell no longer has a nucleus
21
Q
What happens in metaphase in mitosis?
A
- Chromosomes line up along equatorial plane (metaphase plate)
22
Q
What happens in anaphase in mitosis?
A
- Sister chromatids separate, and are push to opposite poles of the cells, centromere first, as spindle fibres contract
23
Q
What happens in telophase in mitosis?
A
- Nucelar membrane reforms
- Chromosomes unfold into chromatin
- Cytokinesis begins
24
Q
What happens in cytokinesis in mitosis?
A
- Cell organelle become evenly distributed around each nucleus
- Cell divides into two daughter cells with a nucleus in each and 46 chromosomes
25
Histologically, how can you tell if a cell is undergoing mitosis?
If the nucleus is dark and the nuclei are not the same size
26
When is something defined as malignant?
If there are too many mitotic figures e.g. lots of dark nuclei of different sizes
27
What are mitotic figures used for?
Determine how bad cancer is - more there are, the worse it is
28
What differentiates meiosis from mitosis?
Meiosis:
- Only in gametes
- Recombination of genetic material results in genetic diversity
- Two cell divisions
- 4 haploid (HALF number of chromosomes - 23) cells produced, which are genetically distinct from each other and the parent cell
- Not a cycle
29
What happens in meiosis I?
- Chromosome number is halved
- In prophase I, crossing over occurs between non-sister chromatids (genes sort independently thus if 1 gene switches over, doesn't mean another one will), resulting in genetic diversity
- In metaphase I, random assortment occurs on the metaphase plate - also resulting in genetic diversity
30
What happens in meiosis II?
- Sister chromatids separate
| - Haploid cells produced
31
What is the first stage of gametogenesis?
The proliferation of primordial (undifferentiated) germ cells (developing gametes) by mitosis
32
What is the process of gametogenesis in males?
- Primordial germ cells to lots of mitoses to spermatogonia (mature sperm)
- Some mitosis occurs in embryonic stages to produce primary spermatocytes present at birth
33
What is the process of gametogenesis in males at puberty?
- Mitosis really begins during puberty and continues throughout life
- Cytoplasm divides evenly
- After meiosis 2 - four equal size gametes
- Millions of mature sperm continually produced
34
How long does the production of mature sperm take?
60-65 days
35
How many sperm are there per ejaculate?
100-200 million
36
What is the process of gametogenesis in females?
- Primordial germ cell to 30 mitoses to oogonia
- Oogonia enter prophase I of meiosis 1 by 8th month of in-utero life
- Process then suspended
37
What is the process of gametogenesis in females at puberty?
- Cells enter ovulation
- Cytoplasm divides unequally (1 egg and 3 polar bodies - PB apoptose)
- Meiosis I is completed at ovulation (there is 1 big cells 1 small cell each with diploid DNA)
- Then goes on to divide again each (after fertilisation) to form 1 big cell (egg) and 3 small cells (polar bodies)
- Meiosis 2 is only completed if fertilisation occurs
38
What is non-disjunction?
Failure of chromosome pairs to separate in meiosis I or sister chromatids to separate properly in meiosis II
39
When does gonadal mosaicism occur?
When precursor germline cells to ova or spermatozoa are a mixture of two or more genetically different cell lines
40
Gonadal mosaicism mainly causes which genetic problems?
Autosomal dominant or X-linked
41
What are the 3 causes of diseases?
Genetic, multifactorial and environmental
42
Give 4 examples of genetic diseases
- Down's syndrome
- Cystic fibrosis
- Huntington disease
- Haemophilia
43
Give 4 examples of multifactorial diseases
- Spina bifida
- Cleft lip/palate
- Diabetes
- Schizophrenia
44
Give 4 examples of environemental diseases
- Poor diet
- Infection
- Drugs
- Accidents
45
Define autosomal
Chromosomes 1-22, all chromosomes except the sex chromosomes (X/Y)
46
Define locus
The position of a gene/DNA on the genetic map
47
Define genotype
Genetic constitution of an individual
48
Define phenotype
Appearance of an individual which results from the interaction of the environment and the genotype
49
Define allele
One of several alternative forms of a gene at a specific locus
- Normal allele is also referred to as wild type
- Disease allele carries the pathogenic mutation
50
Define polymorphism
Frequent hereditary variations at a locus. Doesn't cause problems. They make you more/less efficient or more/less susceptible to disease
51
Define consanguinity
Reproductive union between two relatives
52
Define autozygosity
Homozygous by descent e.g. inheritance of the same mutant allele through two branches of the same family
53
Define homozygous
Both alleles are the same at a locus
54
Define heterozygous
Alleles at a locus are different
55
Define hemizygous
Describes genes that are carried on an unpaired chromosomes. Refers to a locus on an X chromosomes in a male
56
Define penetrance
Proportion of people with a gene/genotype who show the expected phenotype
57
Define complete penetrance
Gene or genes for the trait are expressed in all the population
58
Define incomplete penetrance
The genetic trait is only expressed in parts of the population
59
Define variable expression
Variation in clinical features (type and severity) of a genetic disorder between individuals with the same gene alteration
60
Define sex limitation
Expression of a particular characteristic limited to one of the sexes
61
Define multifactorial condition
Diseases due to a combination of genetic and environmental factors. In relation to family: if a male has condition, then female relatives are more at risk and vice versa (if condition is more prevalent in one sex)
62
Define late-onset
Condition not manifested at birth
63
Define congenital onset
Condition manifested at birth
64
Define autosomal dominant (Mendelian)
- A disease that only manifests in the heterozygous state
- Affects both males and females in equal proportions
- Affected individuals in multiple generations
- Transmission by individuals of both sexes to both sexes
- Only way to pass disease male to male
65
Define autosomal recessive (Mendelian)
- A disease that manifests in the homozygous state
- Two defective genes required
- Healthy siblings have a 2/3 chance of being carriers
- Male and females affected in equal proportions
66
Define X-linked (sex-linked) inheritance (Mendelian)
Caused by a mutation in genes on the X-chromosome
67
Why are X-linked conditions never passed from father to son?
Due to sons getting their X-chromosome from their mother
68
What are the outcomes to offspring of males with an X-linked condition?
- All daughters are carriers
- All sons are unaffected
- Males can never be carriers
69
Define lyonisation
The process of X chromosome inactivation
70
What happens to one of the two X chromosomes in every cell in a female and why?
- It is randomly inactivated early in embryonic development
| - To prevent female cells having twice as many gene products compared to males
71
What happens to the inactive X chromosome in females?
Packaged in heterochromatin (can't be transcprited)
72
What causes sporadic cancers?
2 acquired mutations
73
What causes hereditary cancers?
1 inherited mutation and 1 acquired mutation
74
What is an ideogram?
Diagrammatic form of chromosome bands, bands are numbered according to distance to centromere
75
What are the classifications of genetic disease?
- Chromosomal
- Mendelian (autosomal dominant/recessive or X linked)
- Non-traditional e.g. mitochondrial, imprinting, mosaicism
76
What does a square mean in a genetic pedigree?
Male
77
What does a circle mean in a genetic pedigree?
Female
78
What does a coloured-in object mean in a genetic pedigree?
Affected
79
What is epithelia?
One or more layers of cells that line a body cavity
80
What are the 3 functions of epithelia?
Protection, absorption or secretion
81
Name 4 supporting tissues of the body
- Cartilage
- Bones
- Tendons
- Blood
82
What is the function of supporting tissues?
Structure and protection
83
What are the three types of muscle?
Smooth, skeletal and heart
84
What are the 3 broad types of nerves?
Brain, peripheral and visceral
85
What are the two germ cells?
Ova and sperm
86
What does haemtoxylin stain and what colour?
Acid things - blue
87
What colour does eosin stain and what colour?
Alkaline things - pink
88
What colour does haemotoxylin stain cell nuclei and RNA?
Blue
89
What colour does eosin stain cytoplasm and colloidal proteins?
Pink
90
What colour does eosin stain keratin?
Orange/red
91
What colour does eosin stain extracellular fibres (e.g. collagen and elastic)?
Pink
92
What doesn't stain with H&E?
Extra-cellular jelly & fat
93
What colour does alcian blue stain GAG rich structures?
Blue
94
Where are GAG rich structures found?
In all connective tissue and extracellular matrix
95
What colour does alcian blue stain mucous goblet cells?
Blue
96
What colour does alcian blue stain mast cell granules?
Blue
97
What colour does alcian blue stain the cartilage matrix?
Blue
98
What colour does iron haemotoxylin stain nuclei and elastic fibres?
Black
99
What colour does PAS stain hexose sugars?
Magenta
100
What colour does toluidine blue stain nuclei, ribosomes and cytoplasm?
Dark blue
101
What colour does toluidine blue stain the cartilage matrix and mast cell granules?
Pale blue
102
What colour does toluidine blue stain GAG-rich components?
Bright purple
103
What is the structure of the nucleus of the cell?
- Brain of the cell
| - Double nuclear membrane
104
Where in the cell houses DNA?
The nucleus - in the form of chromatin within the nucleus
105
What is the site of rRNA formation?
The nucleolus
106
What is the site of oxidative phosphorylation?
Mitochondria
107
What is the structure of the mitochondria?
- Double membrane
| - Inner membrane is highly folded
108
What happens in the outer membrane of the mitochondria?
- Lipid synthesis
| - Fatty acid metabolism
109
What happens in the inner membrane of the mitochondria?
Respiratory chain (electron transport) ATP production
110
What happens in the matrix of the mitochondria?
TCA (Krebs') cycle
111
What happens in the intramembranous space of the mitochondria?
Nucelotide phosphorylation (ADP to ATP)
112
What makes RER rough?
Due to numerous ribosomes on the surface
113
What is the site of protein synthesis?
RER
114
What is the structure of the RER?
Highly folded flattened membrane sheets
115
What is the site of membrane lipid synthesis?
SER
116
Where in the cell processes and stores synthesised proteins?
The SER
117
What is the structure of the SER?
Highly folded flattened membrane sheets
118
What is the structure and general function of the Golgi apparatus?
- Parallel stacks of membrane
| - Processes and modifies macromolecules synthesised in the ER
119
What is the function of the cis Golgi?
- Receives SER vesicles
| - Protein phosphorylation occurs here
120
What is the function of the medial Golgi?
- Modifies products by adding sugars
| - Forms complex oligosaccharides by adding sugars to lipids and proteins
121
What is the function of the trans Golgi network?
- Proteolysis of peptides into active forms
| - Sorting molecules into vesicles which bud from the surface
122
In which cells can the Golgi apparatus be clearly seen?
Plasma cells
123
What are vesicles?
Very small, spherical membrane-bound organelles which transport & store material and exchange cell membrane between compartments
124
Name 4 types of vesicles
- Cell-surface derived (pinocytotic & phagocytotic)
- Golgi-dervied
- ER-derived
- Lysosomes & peroxisomes
125
How does the waste-dsiposal system of the lysosomes work?
- H ions are pumped onto membrane
- Creates a low pH to enable acid hydrolases to function
- Break down debris from dead cells
126
What are the functions of peroxisomes?
- Involved in the process which fatty acids are broken down
| - Used to destroy hydrogen peroxide which is a product of FA breakdown.
127
What is the cytoskeleton and what is its function?
- Filamentous proteins which brace the internal structure of the cell
- Helps cells maintain their shape and internal organisation
128
Are cytoskeletons visible in light microscopy?
No
129
Name the 3 filaments of the cytoskeleton in increasing size
- Microfilaments (5nm)
- Intermediate filaments (10nm)
- Microtubules (25nm)
130
Name a microfilament?
Actin
131
How does actin work as a microfilament?
Forms a bracing mesh on the inner surface of the cell membrane
132
How do intermediate filaments work?
Anchored transmembrane proteins which can spread tensile force through tissues
133
Where can cytokeratins be found?
Epithelial cells
134
Where can desmin be found
Myocytes
135
Where can glial fibrillary acidic protein be found and what is its function?
- Astrocytic glial cells
| - Supports neurones in the brain
136
Where can neurofilament protein be found?
Neurones
137
Where can nuclear laminin be found?
Nuclei of all cells
138
Where can vimentin be found?
Mesodermal cells
139
Name a type of microtubule
Tubulin
140
Where do microtubules originate from?
A centrosome
141
In what cells can microtubules be found in?
All cells except from erythrocytes
142
What is lipofuscin?
- Membrane-Bound orange-brown pigment
| - Peroxidation of of lipids in older cells
143
Where is lipofuscin common?
In the heart and liver (sign of wear and tear)
144
How does lipid appear as a storage product?
- Non-membrane bound vacuoles
145
Where is lipid stored in the body?
In adipocytes and liver
146
How does lipid appear histologically?
As empty space
147
What is the structure of glycogen as a storage product?
CHO polymer in cytoplasm
148
Which elements are the molecular building blocks?
Carbon, hydrogen, oxygen, nitrogen, sulphur and phosphate
149
What are macromolecules and what are their functions?
- Simple molecules such as sugars, lipids and amino acids which can form complex large molecules
- Have osmotic, structural, optical, enzymatic and other complex functions
150
Give 5 examples of macromolecules
- Haemoglobin
- DNA
- Glycogen
- Rhodopsin
- Collagen
151
What is the general formula of carbohydrates?
Cn(H2O)n
152
Give 4 examples of general carbohydrates?
- Monosaccharides
- Disaccharides
- Oligosaccharides
- Polysaccharides
153
What is maltose compromised of?
2 x glucose
154
What is sucrose comprised of?
Glucose & fructose
155
What is lactose compromised of?
Glucose & galactose
156
What is the general structure of a monosaccharide?
Chain of carbons, hydroxyl groups and one carbonyl (C=O) group
157
What is an aldose?
A monosaccharide with an aldehyde group
158
What is an ketose?
A monosaccharide with a ketone group
159
What is a chiral centre?
A carbon with 4 different chemical groups
160
What is the difference in D&L monosaccharides?
Have the same chemical properties but different biological ones
161
Are most sugars in living organisms in the D or L form?
D
162
What is a glycosidic bond?
When he hydroxyl group of a monosaccharide can react with an OH or an NH group of another monosaccharide
163
Where are O-glycosidic bonds found?
In disaccharides, oligosaccharides and polysaccharides
164
Where are N-glycosidic bonds found?
In nucleotides and DNA
165
What is an oligosaccharide?
Disaccharide joined by a O-glycosidic bond
166
What is a proteoglycan?
Long, unbranched polysaccharides radiating from a core protein
167
What is the structure of starch?
- Storage in plants
| - Made of amylose (glucose alpha 1,4) and amylopectin (glucose alpha 1,4 & alpha 1,6 glycosidic bonds)
168
What is the structure of glycogen?
- Storage in animals
- Branched polysaccharide formed of glucose residues
- Linking is both alpha 1,4 & alpha 1,6
169
What is a triglyceride compromised of?
3 fatty acids bound to glycerol
170
What happens to the melting point of a lipid with increased fluidity?
Decreases
171
What are the building blocks of DNA?
Nucleotides
172
What are nucleotides compromised of?
A nitrogenous base, pentose sugar and a phosphate group
173
What are the bonds between bases in-between nucleotides?
Hydrogen bonds
174
What are the bonds between phosphate and sugar in nucleotides?
Phosphodiester bonds
175
What is the source of energy in nucleotides?
The phosphate bonds
176
What are the building blocks of proteins?
Amino acids
177
How many amino acids are there?
20
178
What are the structures of amino acids?
Carbon with amino group, carboxyl group and side chain
179
How is the charge of an amino acid determined?
By all three components. Charge changes somewhat with the pH of the solution
180
How is the polarity of the amino acid determined?
By the side chain
181
Are the carboxyl groups of amino acids positive or negative?
Negative
182
Are the amino groups of amino acids positive or negative?
Positive
183
Are amino acids naturally in the D or L form?
L
184
How are peptide bonds formed?
By condensation reaction (water released) between carboxyl group and amino group
185
How are proteins formed?
By linked amino acids which are bonded together by peptide bonds
186
What is the folding of a protein determined by?
- Charged interactions
- Flexibility
- Physical dimensions
187
How is the identity of the protein determined?
By the sequence of amino acids, folding and structure
188
Are peptide bonds stable?
Yes - very
189
How are peptide bonds cleaved?
Proteolytic enzymes - proteases or peptidases
190
What is a protein?
A large polypeptide, usually form 10s to 1000s of amino acids
191
What is the function of a protein dependent on?
Structure
192
What is the primary structure of a protein?
A linear sequence of amino acids, held together by covalent bonds
193
What is the secondary structure of a protein?
Formation of either alpha helix or beta pleated sheets due to hydrogen bonds between amino acids - determined by the local interactions between the side chains and sequence of amino acids
194
What is a super-secondary structure of a protein?
Combination of secondary structures
195
What is the tertiary structure of a protein?
- Overall 3D conformation of a protein
- Bonding involved is electrostatic, H-bonds and covalent bonds
- This occurs due to ionic bonds, disulphide bridges or Van Der Waals forces
196
What is the quaternary structure of a protein?
- 3D structure of protein composed of multiple subunits
- Same non-covalent interactions as tertiary structures
- 2 or more tertiary structure joined together to form a protein
197
What are the 5 forces which hold proteins together?
- Van der Waals forces
- Hydrogen bonds
- Hydrophobic forces
- Ionic bonds
- Disulphide bonds
198
What is a Van der Waals force?
Weak attractive/repulsive force between all atoms due to fluctuating electrical charge
199
What is a hydrogen bond?
Interaction between polar groups
200
What is a hydrophobic force?
As uncharged and non-polar side chain are repelled by water, these hydrophobic side chains tend to form tightly packed cores in the interior of proteins, excluding water molecules.
201
What is an ionic bond?
- Between fully/partially charged groups
| - Weakened in aq systems by water molecules and other ions in solution
202
What are disulphide bonds?
Very strong covalent bonds between sulphur atoms
203
Name 6 factors which influence the rate of reaction
- Temperature
- pH
- Conc of reactants
- Catalyst
- SA of solid reactant
- Pressure of gaseous reactants/products
204
How can enzymes be used for diagnostic purposes?
As they control metabolism they can be used for disease markers
205
What is the primitive function of enzymes?
Provide an alternative reaction pathway with a lower activation energy
206
How do enzymes work?
Bind the substrates and convert them to products, they then release the products and return to their original form
207
How can enzymes be regulated?
By altering the concentration of substrates, products, inhibitors or activators
208
What is a isoenzyme?
Enzymes which have a different structure and sequence but catalyse the same reaction
209
What is a coenzyme?
They can't catalyse a reaction themselves, but can help enzymes to do so. They can bind with the enzyme protein molecule to form the active enzyme
210
What are activation-transfer coenzymes?
Form a covalent bond and are regenerated at the end of the reaction
211
What are oxidation-reduction coenzymes?
Involved in reactions where electrons are transferred from one compound to the other
212
What is haemoglobin and where is it found?
- Found in red blood cells
| - Oxygen carrier in blood
213
What is myoglobin and where is it found?
- Serves as a reserve supply of oxygen
- Facilitates the movement of oxygen in muscles
- Found in muscles
214
Are myoglobin and haemoglobin the same?
They have the same tertiary structure but not quaternary
215
What is at the core of both haemoglobin and myoglobin?
The porphyrin ring which holds an iron atom
216
Name 3 broad factors which influence haemoglobin saturation?
- Partial pressure of O2 in blood, as it increases so does haemoglobin saturation
- Temperature, H+ and partial pressure of CO2
- Sickle cell anaemia
217
How do temperature, H+ and partial pressure of CO2 influence haemoglobin saturation?
All modify the structure of haemoglobin and alter its affinity for O2
218
What is another name for immunoglobulins?
Antibodies
219
What is the main function of immunoglobulins?
To bind to antigens
220
What are antibodies produced for?
To bind to antigens on toxins or proteins
221
Is antibody-antigen binding specific?
Yes - one antibody only matches one antigen
222
How are antigens bound to the antibody?
- By the variable domain
| - Amino acid in the variable domain can be varied to produce an infinite variety of foreign antigens
223
Where is DNA found?
- The nucleus
| - The mitochondria (purely maternal DNA)
224
What is the structure of DNA in prokaryotes?
No nuclear membrane, DNA arranged often in single chromosome
225
What is the structure of DNA in eukaryotes?
- DNA is in the nucleus, bound to proteins (chromatin complex)
226
What are the functions of DNA?
- A template and regulator for transcription and protein synthesis
- DNA is the genetic material thus the structural basis of hereditary and genetic diseases
227
What is the structure of nucleic acids
- The building blocks to make new DNA
| - Free phosphate groups provide energy for the reaction to go through
228
How does DNA polymerase read the template strand?
From 3' to 5' thus DNA is synthesised on the daughter strand from 5' to 3' as DNA runs antiparallel
229
What is phosphate at 5' of DNA used for?
A source of energy for the reaction of DNA synthesis to occur
230
Why is DNA replication semi-conservative?
Because each resulting DNA double helix retains one strand of the original DNA
231
What are the enzymes and proteins involved in DNA replication?
- Topoisomerase
- DNA helicase
- DNA polymerase
- Primer
- Single strand binding protein
- Primase enzyme
- RNAse H
232
What is the function of topoisomerase?
Unwinds the double helix by relieving the supercoils
233
What is the function of DNA helicase?
Separates the DNA apart, by breaking hydrogen bonds between bases, exposing nucleotides
234
What is the function of DNA polymerase?
Reads 3' to 5' and synthesises DNA on daughter strand 5' to 3' - creates DNA by working in pairs to make 2 new strands of DNA. Starts at primer.
235
What is the function of a primer?
A short strand of DNA that is the start point for DNA synthesis as DNA polymerases can only add nucleotides on to an existing strand of DNA
236
What is a single strand binding protein?
Keeps two strands of DNA apart whilst synthesis of new DNA occurs - prevents annealing to form double stranded DNA
237
What is the function of primase?
RNA polymerase that synthesises the short RNA primers needed to start the strand replication process
238
What is the function of RNAse H?
Removes the RNA primers that previously began the DNA strand synthesis
