GENETICS

Question 1

What is gonadal mosaicism?

Answer 1

where more than one set of genetic information is found specifically within the gamete cells

Question 2

What is non-disjunction?

Answer 2

Failure of homologous chromosomes or sister chromatids to separate properly

Question 3

What is autosomal dominant inheritance, the chance of offspring having the condition and an example condition?

Answer 3

offspring to be heterozygous

huntingtons disease

Question 4

What is a centromere and telomere

Answer 4

centromere- how chromosomes are attached to each other
attached to spindle fibre during cell division

telomere- the end of a chromosome. Telomeres are made of repetitive sequences of non-coding DNA that protect the chromosome from damage

Question 5

How does meiosis produce genetically different cells?

Answer 5

through crossing over and independent assortment

Question 6

what is a mis sense mutation

Answer 6

point mutation in which a single nucleotide tide change results in a codon that codes for a different amino acid

Question 7

What is a non-sense mutation , and an example?

Answer 7

where a codon is changed to a premature stopcodon that results in a truncation of the resulting protein, can render the protein non functional

Question 8

what is aneuploidy

Answer 8

Aneuploidy is the presence in a cell of an atypical number of chromosomes.

Question 9

Stages in mitosis

Answer 9

Interphase dna replicates
Prophase dna condenses and formation of spindles
Metaphase chromosomes line up along the centre and spindles attach to centromeres
Anaphase chromosomes split and go to opposite poles
Telophase nuclear membrane begin to form , microfilament ring tightens
Cytokinesis two seperate daughter cells when the membrane seperates

Question 10

Steps in meiosis

Answer 10

M1- mitosis 1
Dna replicates prophase
Crossing over for genetic diversity
Independent segregation in metaphase maternal and paternal chromosomes line up along the equator
Anaphase 1 dna is divided in 2
Telophase 2 haploid cells
Same process again but with 4 genetically different cells at the end

Question 11

Define penetrance

Answer 11

Proportion of individuals carrying a particular variant

Question 12

Variable expression

Answer 12

Degree in which a genotype is expressed in the phenotype

Question 13

Define sex limitation

Answer 13

Genes that are present in both sexes but are only expressed in one gene

Question 14

What is gametogenesis

Answer 14

Process by which diploid or haploid cells undergo cell division and differentiation to make mature haploid cells

Question 15

What is a Mendelian trait

Answer 15

One that is controlled by a single locus in an inheritance pattern

Question 16

What is the knudson hypothesis

Answer 16

Hypothesis that most tumor supressor genes require both alleles to be inactivated

Question 17

what parts of the cell cycle are classed as interphase

Answer 17

g1 g2 s1

Question 18

what happens in g1 s and g2

Answer 18

g1 organelles replicate
s dna replication
g2- preparation for mitosis,

Question 19

what happens at g1 and g2 checkpoint

Answer 19

g1- checks dna damage pre dna repl

g2- checks dna damage after rep, damaged bases are removed

Question 20

define polymorphism

Answer 20

Two or more variants of a particular DNA sequence

Question 21

what is wild type

Answer 21

the normal expression of a genen

Question 22

what is anticipation

Answer 22

eg huntingtons

wider nucleotide repeats through generations

Question 23

what is autozygocity

Answer 23

mutation from both parents

Question 24

Rules of inheritance for autosomal recessive

Answer 24

Appears in both sexes with equal frequency
Tends to skip a generation
more frequent in consanguineous marriages

Question 25

Rules of inheritance for autosomal dominant

Answer 25

Does not skip generation
Male and female equally affected
Unaffected parents do not transmit the trait

Question 26

X linked dominant rules

Answer 26

More often female than male affected
No skipping of generations
Affected sons must have an affected mother

Question 27

X linked recessive rules

Answer 27

More males than females affected
Affected sons are born to unaffected mothers
Trait does skip generation
Never passed from father to son

Question 28

Mitochondrial inheritance rules

Answer 28

Trait inherited from mother only

All children of mother are at risk to be affected or carriers