Genetics semester 1 Flashcards
(204 cards)
1
Q
What are Mendels three laws?
A
- Segregation
- Independent assortment
- Dominance
2
Q
Is a amoebe unicellular or multicellular?
A
Unicellular.
3
Q
When mating types 1 and 2 meet what happens?
A
They form a plasmodium.
4
Q
What do plasmodium eat?
A
Amoebe.
5
Q
Does the plasmodium show the genotype or the phenotype?
A
Genotype.
6
Q
Do the plasmodium have a type?
A
No.
7
Q
What are aspergillus nidulans?
A
Asexual spores with one nuclei and a coloured pigment.
8
Q
What colour is mycelium?
A
They are colourless.
9
Q
Do conidia or mycleium have thread like hyphae?
A
Mycleium.
10
Q
Where do the conidia get their colour from?
A
Through the colourless mycelium.
11
Q
What two processes make up nuclear cell division?
A
Karykinesis and cytokinesis.
12
Q
What is the definition of variance?
A
Tendency for offspring to differ from parents.
13
Q
What is the definition of heredity?
A
Tendency of offspring to resemble parents.
14
Q
What did Jennifer Dees experiment with mating type show?
A
That there is more than one allele per gene.
15
Q
What is chimera?
A
When there is more than one genotype per zygote. This is naturally rare in humans.
16
Q
What is the definition of totipotency?
A
Ability of a cell to give rise to a whole new organism.
17
Q
What is cytogenetics?
A
The connection between the behaviour of chromosomes and the behaviour of genes.
18
Q
What is a centromere?
A
The constriction on each chromosome.
19
Q
How many identical cells does there need to be for it to be considered a clone.
A
More than 2.
20
Q
There are 10^14 clone cells in the body with how many different morphogens?
A
200.
21
Q
What are two consequences of mutations?
A
Apoptosis or cancer.
22
Q
Do haploid or diploid organisms go through mutations?
A
Both.
23
Q
Is AB/ ab described as cis or trans?
A
Cis.
24
Q
Is Ab/Ba described as cis or trans?
A
Trans.
25
What are the ends of chromosomes called?
Telomeres.
26
What arm is (P)?
The short arm.
27
What arm is (Q)?
The long arm.
28
What is chromatin a mix of?
Protein and DNA.
29
What protolytic enzyme allows G banding?
Tripsin.
30
What is the stain called that G banding is involved in?
Giasma stain.
31
Which sex chromosome is smaller?
Y.
32
What type of proteins allow sister chromatid cohesion?
Glue proteins.
33
What happens at the end of the spindle fibres allowing them to shorten?
Depolymerisation.
34
What is euchrochromatin?
Loose DNA which is transcribed.
35
What is heterochromatin?
Tight DNA that is not transcribed.
36
What can prophase be separated into?
Prophase and prometaphase.
37
What is nordisjuction?
Failure of normal segregation.
38
What does the chiasma do?
Helps hold the bivalents together.
39
What disorder does XO show?
Turner syndrome.
40
What disorder does XXY show?
Sex klinefelter.
41
What is the genetic notation for a Down's syndrome female?
47 XX +21
42
What is the notation for Cri Du Chat?
46 XX 5P-
43
What is the definition of heredity?
Transmission of characteristics from parents to offspring by the means of genes.
44
What does aneuploidy mean?
An incomplete set of genes. Either too many or not enough.
45
What type of aneuploidy is trisomic?
2n+1.
46
What type of aneuploidy is monosomic?
2n-1.
47
What type of aneuploidy is nuclisomic?
2n-2.
48
What type of aneuploidy is disomic?
n+1.
49
Duplication can be tandem or ______.
Insertional.
50
What happens in an inversion of DNA?
The segment is cut out, flipped and reversed.
51
In a paracentric inversion is the centromere inside or outside?
Paracentric- outside
| Pericentric- inside.
52
How many chromosomes are there before and after mitosis?
46
There are 92 chromatids before and no chromatids after.
53
Is meiosis 1 or 2 a reduction division?
1.
54
Is meiosis 1 or 2 an equational division?
2.
55
When do bivalents form in meiosis?
Prophase 1.
56
What type of segregation happens in tetrads.
2:2 segregation.
57
Is Mendels law of independent assortment always true?
No.
58
What holds together tetrads?
Membrane sacs called ascus.
59
What type off cross over do you need to make a tetrad with a non parental diatype?
A double cross over.
60
What needs to be restrained to get ordered tetrads?
Meiosis.
61
For a tetrad to be all recombinant what needs to happen?
A four strand double cross over.
62
When there are no cross overs what type of segregation has occurred?
First division segregation.
63
When one cross over has occurred when type of segregation has happened?
Second degree segregation.
64
The probability of a cross over between two genes is roughly proportional too?
The distance between them.
65
What holds chromosomes together until anaphase 1?
Cross overs.
66
If a cross over is unlikely are there more parentals or recombinants in the progeny?
Parentals.
67
In tetrads if there is less NPD then P what can it show?
Linkage.
68
What does Mendels second law not apply too?
Linked genes.
69
What does the recombination frequency equal?
Recombinants/ total meiotic products x 100.
70
Why is the maximum combination frequency 50%?
Because if the genes lie far enough apart is it equally likely that they will be P or R.
71
What does a polymorphic population mean?
Two or more alleles are present at a significant frequency of more than one.
72
How do you calculate allele frequency?
)No. of allele A)/ 2N.
73
What 3 assumptions do you have to make for Hardy Weinburg to be true?
No mutation, no migration, random genetic drift.
74
What is the founders effect?
When a breeding female moves out of a population to make a new one, for example on the Galápagos Islands.
75
What does positive assortative mating involve?
Choosing a mate if they have the same phenotype as you.
76
What does positive assortative mating occurs what to do you end up with more off?
More homozygous in the population.
Allele frequency is not changed.
77
What does negative assortative mating ( avoiding choosing a mate with similar characteristics as yourself) increase?
The frequency of heterozygous in a population.
78
When will natural selection not act against an allele?
When it has no effect on the phenotype.
79
What can transient polymorphism be followed by?
Fixation of an old or new allele.
80
What is pleiotropy?
When one gene affects more than one phenotype.
81
What are the three types of dominance?
Simple, incomplete and over dominance.
82
What does Darwinian fitness show (W)?
The ability for an individual to pass on a gene.
83
What is S?
The selection coefficient.
84
What equation relates W and S?
W = 1-S.
85
If selection is acting against a recessive allele what genotype will increase in the next generation?
Homozygous dominant.
86
What happens as allele frequency decreases?
Selection is less efficient.
87
What equals the percentage of A in the homozygote?
The frequency of the recessive allele.
88
What can selection against an allele be balanced by?
Mutation to that allele.
89
There is a high frequency of the allele for cystic fibrosis. Why is this believed to be the case?
It is thought that in the past there was a heterozygous advantage for a increased resistance to cholera in mice and an increased resistance to tb in humans.
90
How many people carry cystic fibrosis?
1 in 22.
91
What happens mutagenesis?
A wrong base is incorporated into the replication fork. This happens in S phase.
92
What is an independent mutant?
A mutant which has arised from a independent mutation event.
93
How do you determine how many mutations a mutant carries?
Cross with a wild type.
94
What ratio is found when there is one mutant?
1:1.
95
What ratio is found when there are more than one mutant?
1:3 or 3:1. That downers on wether having one mutant shows the mutant phenotype.
96
What does allied mutants mean?
Mutants are on the same gene.
97
What does non alleleic mutants mean?
Mutants are on a different gene.
98
What two tests can you use to test for allelism?
Recombination or complementation test.
99
In the test of recombination do allelic or non allelic mutants give rise to a wild type?
Non allelic.
100
What genes could you mistake for allelic in the recombination test?
Genes which are closely linked.
101
How are genes with related functions often organised throughout the genome?
They are spread out.
102
In the complementation test what do you look at?
The diploid phenotype.
103
In the complementation test what will allelic mutants give rise to?
A mutant diploid.
104
In the complementation test what will non allelic mutants give rise to?
A wild type diploid.
105
For complementation to work what do all mutants have to be?
Recessive.
106
What is a complementation group?
A set of mutants that fail to compleat each other, therefore identifies a gene.
107
Apart from diploids, what else can the complementation test be used on?
Heterokaryons (cells with more than one haploid nucleus, such as fungi.)
108
Why does it not matter in a heterokaryon that the WT are in different nuclei?
Protein synthesis occurs in the cytoplasm.
109
What order is the birth order shown as on a human pedigree?
Left to right.
110
What is a proposituts/ proband/ proposita?
An individual which brought that human pedigree to attention.
111
What is penetrance?
Proportion of individuals with a particular genotype which the corresponding phenotype.
112
What is expressivity?
The extent that individual with a particular genotype shows the corresponding phenotype.
113
On a probability tree do you follow genotypes or phenotypes?
Phenotypes.
114
What is a physical map based on?
Gene sequence directly.
115
What is a linkage group?
A set of gene loci that are known to lie on the same chromosome.
116
What two steps does mapping a gene involve?
1. Assignment to a linkage group.
| 2. Determining the position within a linkage group.
117
Why can't a normal cross be used to show linkage?
As for 15/16 of the progeny the exact genotype may not be known.
118
What does a test cross involve?
A double heterozygous parent and a homozygous recessive parent.
119
What do test crosses allow you to do?
Work out the recombination frequency and with it construct a linkage map.
Note in haploids you can directly look at mitotic products.
120
How are cytological maps made?
Visualising DNA to check for any visible mutations.
121
What can a linkage of 50% also show?
That genes lie on different chromosomes.
122
What is the purpose of a three point cross?
To determine the relative map position if three genes which lie in a single linkage group.
123
What is a double cross over?
When a group is mistaken as parental with respect to the flanking makers.
124
What is a cM equivalent too?
I cross over per 100 gametes.
125
What is the equation for map distance?
(SC1 + SC2 + 2DCO) / 100
126
Do double cross overs cause the map distance to be over or underestimate the distance of the flanking markers?
Overestimate.
127
What's the best way to estimate map distance?
The sum of the intermediate RFs.
128
Up until what percentage is there a linear relationship between cM and RF? Why?
10%
| As at small distances there is less chance of generating double cross overs.
129
What class is always the largest class when looking at constructing a three point cross?
The parental.
130
What class is the smallest class when constructing a three point cross?
The DCO class.
131
What is interference?
The occurs be of one crossover may effect the chance of another cross over near by.
132
How can you show interference?
By looking at the actual number of DCO and calculating the expected amount of double cross overs with the product rule. The numbers will not add up as the events are not independent.
133
What is the coefficient of coincidence?
Observed DCO/ Expected DCO.
134
If the coefficient of coincidence is 0 what does this show?
High interference / cross overs are very close together.
135
What is the equation for interference?
1- coefficient of coincidence.
136
Do mitochondrial genes for Mendelian inheritance?
No.
137
What is Anisogomy?
Gametes are dimorphic.
138
What is isogamy?
Gametes are morphologically identical.
139
Is isogamy is maternal inheritance followed?
Almost always but is called uniparental.
140
How big is the human mitochondrial genome?
17kb.
141
What is encode for by mitochondrial DNA?
Genes for protein synthesis machinery and genes for subunits of the mitrochondrial electron transport chain.
142
What is LHON?
Leber's Heredity Optic Neuropathy / a disease caused by mutations in mitrochondrial DNA.
143
What is heteroplasmon?
A cell with more than one genotype. Often due to mutation.
144
What is a homoplasmon?
A cell with one genotype. All cytoplasmic genomes are the same.
145
In a heteroplasmon do you need the wild type genotype of the mitochondrial DNA to be alive?
Yes.
146
How long is M phase?
30-45 minutes.
147
How long is S phase?
6-8 hours.
148
How long is G1?
6-8 hours.
149
How long is G2?
4-6 hours.
150
What is the MTOC?
Microtubule organising centre.
151
What is the animal MTOC composed off?
2 centrioles and tubulin subunits. It is a double structure.
152
When so the spindles attach to the centromeres?
When the nuclear envelope breaks down.
153
What is the metaphase plate?
It represents chromosomes on the equator of the spindle.
154
What is disjunction?
When anaphase separates chromosomes.
155
Where are kinetochore proteins found?
At the centromere.
156
What enzyme breaks down sister chromatid cohesion?
Separase.
157
What is present at the centromere to prevent separase from acting?
Shugoshin.
158
What does the kinetochore interact with?
Ends of microtubulin in the spindle.
159
What end do microtubules grow from?
Positive end.
160
What do the astral microtubules do?
Anchor the spindles and MTOC to the cell cortex.
161
What ends are present at the MTOC?
Negative.
162
What happens to the kinetochore microtubules in anaphase one?
Motor proteins move towards the negative end causing depolymerisation and shortening.
163
What happens to the polar microtubules in anaphase 2?
They lengthen due to polymerisation at the negative end. Motor proteins move towards the positive ends.
164
What happens to the astral microtubules in anaphase 2?
The polar ends extend and they shorten. Motor proteins cause depolymerisation at the positive end.
165
What type of microtubule does the centromere attach to?
Kinetochore microtubule.
166
What is a conditional mutant?
A mutant than can only progress through one of two conditions. If it can progress through both then it is WT.
167
What did Hartwell discover?
CDC.
168
What temperature is permissive/ non restrictive?
Low.
169
What temperature is non permissive/ restrictive?
High.
170
What is a selective technique?
A technique where only one phenotype can survive- the best technique to use.
171
What technique did Hatwell use?
The screening technique with velvet replica planting.
172
What two temperatures did Hartwell use?
23 and 36.
173
What does a asynchronous population contain?
Cells at all stages of the cell cycle.
174
What does CDC28 do?
Play a key role in the initial decision of if the cell should proceed through the cycle.
175
What organism did Nurse use to isolate CDC?
S. Pombe.
176
What does CDC2 control?
G2 progressing into M.
177
What corresponding gene to CDC28/ CDC2 is found in humans?
CDK1.
178
What did Hunt discover?
Cyclins.
179
When is cycling synthesised?
Continuously.
180
When is cycling destroyed?
During mitosis.
181
CDC28, CDC2 and CDK1 are all what?
Cycling dependant protein kinases.
182
What does progression through the cell cycle dependant on?
Cycling availability.
183
What cyclin dependant kinase is found in yeast?
CDC28. It does however have more than one cyclin.
184
Do mammals have multiple cyclin dependant kinases?
Yes. They also have multiple cyclins.
185
When is mitotic cyclin at critical concentration?
At the end of G2.
186
When CDK and cyclin form the active complex what do they do?
Carry our phosphorylation activities including targeting protein degradation.
187
How does the cyclin/CDK complex become active?
It is phosphorylated by other kinases.
188
How are the 2 inhibitory phosphates removed?
Phosphatase activity from the active form of CDK/cyclin.
189
How many activating phosphates are associated with CDK/ cyclin complex?
One.
190
What type of feedback does the CDK/cyclin complex use?
Positive.
191
How is the anaphase promoting complex switched on?
It is phosphorylated by the CDK/cyclin complex.
192
What does the anaphase promoting complex do?
Promotes separase activity by targeting securin for degradation.
193
What is separase complexes with?
Securin.
194
How can you activate separase?
Degrade securin.
195
What is APG?
A ubiquitin ligase. It targets other proteins to be destroyed.
196
What does G1 CDK/cyclin do?
Decides if the cell should leave G1 and enter S phase.
197
What activates EF2 transcription factor?
G1 CDK/cyclin.
198
What is EF2 normally bound to?
Rb protein.
199
How is rb destroyed?
It is directly phosphorylated by G1 CDK/cyclin.
200
What are checkpoints also known as?
Transition points.
201
What checkpoint commits the cell to completing the cycle?
G1 checkpoint.
202
When is DNA damage permanently incorporated into the genome?
Once it has gone through a phase and passed the replication fork.
203
What does the G2 checkpoint check?
If the cell is ready to divide.
204
What does the metaphase checkpoint check?
If all the chromosomes are attached to the spindle.
