Genes

Question 1

Genotype =

Answer 1

the alleles present at a given locus

Question 2

Autosome =

Answer 2

Chromosomes that aren’t the sex chromosomes

Question 3

Gene =

Answer 3

A sequence of nucleic acids that contribute to the phenotype

Question 4

Loci =

Answer 4

A location on the chromosome

Question 5

Phenotype =

Answer 5

The observable characteristics as a result of the genotype

Question 6

What is the Central Dogma? And who named it?

Answer 6

An explanation of the flow of genetic information in a biological system
DNA —-> RNA —-> Protein
Named by Francis Crick

Question 7

G x E =

Answer 7

genetic x environmental interaction = effects the phenotype

Question 8

Pleiotropy =

Answer 8

one gene influences two or more seemingly unrelated phenotypic traits

Question 9

Polygenic traits =

Answer 9

a trait effected by many genes e.g. height

Question 10

Processes that don’t fit the central dogma like epigenetic inheritance, don’t fit because…

Answer 10

DNA is still the ‘information’ source but the process is not sequence dependant

Question 11

sources of change to the genotype:

Answer 11

1. mutations

2. recombination of alleles during meiosis

Question 12

three types of changes to the DNA sequence:

Answer 12

1. Base pair substitutions
2. Duplication
3. Deletion

Question 13

Base pair substitutions:

transitions =

Answer 13

a change of base; either purine to purine or pyrimidine to pyrimidine

Question 14

Base pair substitutions:

transversions =

Answer 14

a change in base; either purine to pyrimidine to purine or purine to pyrimidine

Question 15

Purine bases =

Answer 15

guanine and adenine

Question 16

Pyrimidine bases =

Answer 16

cytosine and thymine

Question 17

duplication =

Answer 17

when a base is accidentally duplicated e.g:

CTACG ——> CTAACG

Question 18

deletion =

Answer 18

when a base is accidentally deleted e.g:

CTGACG ———> CTG_CG

Question 19

which can be inherited: mutations in the somatic cells or the germline cells?

Answer 19

Only in the germline cells, somatic mutations cannot be passed down

Question 20

Inversion =

Answer 20

orders of genes at a locus have been swapped with each other

Question 21

Translocation =

Answer 21

When the end of a chromosome has been copied and pasted onto the end of another, resulting in varying lengths of chromosome pairs

Question 22

Errors of chromosomal dose can cause…

Answer 22

Conditions such as Down syndrome (trisomy of chromosome 21 occurs as non-disjunction happens during cell division)

Question 23

females have 2 X chromosomes and males have 1, to equalise the X dose between males and females, what happens?

Answer 23

In females, 1 X chromosome is randomly silenced or inactivated

Question 24

females are said to be mosaic for inactivated X chromosomes, what does this mean?

Answer 24

In different cells in the body, a different X chromosome may be silenced.

Question 25

Even though there are more possible transversions than transitions, transitions are more likely to occur, why is this?

Answer 25

substituting a single ring for another single ring or a double ring to another double ring is more likely than substituting single for double or vice versa.

Question 26

synonymous mutations =

Answer 26

when the base change doesn't change the amino acid coded for

Question 27

non-synonymous mutations =

Answer 27

when the base change does change the amino acid coded for

Question 28

frame shift mutations =

Answer 28

a bases insertion or deletion causes a frameshift and therefore a change in the amino acids coded for.

Question 29

``` Mitosis or Meiosis? •Ploidy halved •Produces 4 cells •Homologous chromosomes pair •Recombination between homologues ```

Answer 29

Meiosis

Question 30

``` Mitosis or Meiosis? •Ploidy maintained •Produces 2 cells •Homologues don’t pair •No recombination ```

Answer 30

Mitosis

Question 31

Ploidy =

Answer 31

Ploidy is the number of complete sets of chromosomes in a cell

Question 32

Order of mitosis: | Hint: I Prefer Milk And Tea

Answer 32

1. Interphase 2. Prophase 3. Metaphase 4. Anaphase 5. Telophase and cytokinesis

Question 33

Order of meiosis? | Hint: I Prefer Milk And Tea x2

Answer 33

1. Interphase 1 6. Interphase 2 2. Prophase 1 7. Prophase 2 3. Metaphase 1 8. Metaphase 2 4. Anaphase 1 9. Anaphase 2 5. Telophase1+cytokinesis 10. Telophase2+cytokinesis

Question 34

Mitosis or meiosis? | 2n -> 4n -> 2n

Answer 34

Mitosis

Question 35

Mitosis or Meiosis? | 2n -> 4n -> 2n -> n

Answer 35

Meiosis

Question 36

Genetic consequences of meiosis =

Answer 36

1. Parental chromosomes are changed 2. Different combinations of alleles 3. Unique mixture of recombined chromosomes 4. After fertilisation, new pairings of chromosomes

Question 37

Recombination is: 1. More likely between physically________ positions 2. Very unlikely between very_________ positions 3. Less likely at chromosome__________.

Answer 37

Far Close Ends

Question 38

Asexual reproduction: Agametic =

Answer 38

* Budding or fission | * Offspring are genetically identical to the parents

Question 39

Asexual reproduction: Parthenogenesis =

Answer 39

* Gametes produced by mitosis or a modified meiosis | * Offspring are identical to the parents, and to each other

Question 40

What equation can we use to calculate genotype frequencies in a population?

Answer 40

Hardy Weinberg Equation: | a² + 2(ab) + b² = 1

Question 41

In a population of otters (Lutra lutra) in Scotland there are two alleles at a locus of interest. Allele A has a frequency of 0.7 and allele B a frequency of 0.3 What proportion of each genotype would you expect in such a population if it was at Hardy-Weinberg equilibrium?

Answer 41

``` AA = 0.49 AB = 0.42 BB = 0.09 ```

Question 42

karyotype =

Answer 42

the complete set of chromosomes of an individual

Question 43

Synteny =

Answer 43

Conservation of regions of chromosomes between species

Question 44

Homologue =

Answer 44

genes that share a (hypothesised) common ancestor

Question 45

Orthologue =

Answer 45

genes that share a common ancestor but have separated with speciation

Question 46

Paralogue =

Answer 46

descendants of a duplicated gene

Question 47

Euploid =

Answer 47

A change in the number of complete sets of chromosomes e.g 4n --> 5n

Question 48

Aneuploid =

Answer 48

change in the number of individual chromosomes e.g | 46 ---> 47 (Down syndrome)

Question 49

Autopolyploid =

Answer 49

chromosomes coming from one species

Question 50

Allopolyploid =

Answer 50

Chromosomes coming from different species