Genes and Inheritance

Question 1

What are the stages of mitosis

Answer 1

Interphase, Prophase, Metaphase, Anaphase and Telophase

Question 2

What happens in interphase

Answer 2

Chromosomes are diffuse (uncondensed and not visible)
RNA and protein synthesis
DNA Synthesis during S Phase
Cell Growth

Question 3

What happens in prophase

Answer 3

replicated chromosomes become visible
comprised of sister chromatids joined by centromeres
the nuclear membrane breaks down
centrioles move to opposite poles, with spindle fibres produced between them

Question 4

what happens in metaphase

Answer 4

chromosomes attach to the spindle fibres by the kinetochores
line up in the equator of the spindle
chromosomes are now at the most condensed state and visible

Question 5

What happens during anaphase

Answer 5

centromeres divide

sister chromatids pulled apart to the poles by connecting spindle fibres

Question 6

what happens during telophase

Answer 6

nuclear membranes reform
the chromosomes decondense
the daughter cells return to interphase

Question 7

why have chromosomes condensed

Answer 7

serve to manoeuvre DNA through cell division

all the cell to avoid getting knotted DNA

Question 8

What untangles DNA and how

Answer 8

topoisomerase

briefly cut and rejoin DNA

Question 9

What are somatic cells (chromosomal speaking)

Answer 9

Diploid

Question 10

What are germ cells (chromosomal speaking)

Answer 10

Diploid or haploid

Question 11

What is meiosis

Answer 11

the reduction of chromosomal numbers from diploid to haploid

Question 12

What are the stages of meiosis

Answer 12

Prophase I
Metaphase I
Anaphase I
Telophase I

Prophase II
Metaphase II
Anaphase II
Telophase II

Question 13

What is a leptotene

Answer 13

when chromosomes first become visible as thin threads within the nucleus

Question 14

What is a zygotene

Answer 14

the homologous pairs of chromosomes which become closely associated along their lengths by a process called synapsis, to form bivalents

Question 15

what is a pachytene

Answer 15

synapsis is complete and the bivalents are held together throughout their length by a structure known as the synaptonemal complex

Question 16

What is recombination

Answer 16

Homologous chromosomes cross over and swap homologous sections of their DNA

Question 17

what is diplotene

Answer 17

the homologous chromosomes appear to repel each other and remain her together only at chiasmata and at the centromere

Question 18

what is the chromosomal number during prophase II, metaphase II and anaphase II

Answer 18

haploid

Question 19

What happens during the second mimic division in the egg

Answer 19

the second mitotic division is not complete until fertilisation, and is very unequal, giving the mature egg and a small polar body

Question 20

What are Mendel’s two laws

Answer 20

Segregation of characterises

Independant assortment

Question 21

What is segregation of characteristics

Answer 21

when a pair of characteristics that is only represented in one gamete

Question 22

What is genetic dominance

Answer 22

when a gene for a characteristic has one dominant allele which stresses the manifestation of the second recessive allele

Question 23

What is an example of an autosomal recessive disease

Answer 23

Cystic Fibrosis

Question 24

What are 3 examples of autosomal dominant diseases

Answer 24

Tuberous sclerosis
Neurofibromatosis
Retinoblastoma

Question 25

What is Independent Assortment

Answer 25

Two characteristics that are inherited independently

Question 26

What does it mean to describe genes as linked

Answer 26

They are located near each other on a chromosome

Question 27

What is Sex Linkage

Answer 27

Genes that are carried and inherited via the X and Y chromosomes

Question 28

Why are males more affected by sex-linked diseases

Answer 28

Males are homozygous, and so recessive alleles manifest themselves in the male phenotype

Question 29

What are 3 key features of an X-linked recessive pedigree

Answer 29

Clusters of affected males Affected males connected through unaffected females No male to male transmission

Question 30

What are the two Hardy-Weinberg Equilibrium equations

Answer 30

p + q = 1 p^2 + 2pq + q^2 = 1

Question 31

What are the 5 conditions of Hardy-Weinberg

Answer 31

``` Infinite population Random mating No selection pressures No new alleles by mutation No net migration into/out of population ```

Question 32

What is the human karyotype

Answer 32

``` 44 autosomes (22 pairs) 2 sex chromosomes ```

Question 33

When are chromosomes most condensed and visible

Answer 33

during metaphase

Question 34

What are DNA molecules wrapped around

Answer 34

Histone proteins

Question 35

What is a histone wrapped with DNA called

Answer 35

Nucleosome

Question 36

What is a bundle of nucleosomes called

Answer 36

Chromatin Fibre

Question 37

What do Chromatin Fibres bind to

Answer 37

Scaffold

Question 38

What does loops of chromatin fibre form

Answer 38

Chromatid

Question 39

What are two chromatids joined together called

Answer 39

Sister Chromatids

Question 40

What hold the sister chromatids together

Answer 40

The centromere

Question 41

What are the names of the different grooves in DNA

Answer 41

Major and Minor Groove

Question 42

What are telomeres

Answer 42

Short tenderly repeating sequences that prevent DNA fusing and karyotype re-arrangement Maintain the length of the germ-line cells

Question 43

What natural process causes shortening of telomeres

Answer 43

Ageing

Question 44

What is X inactivation

Answer 44

When a maternal chromosome condenses, silencing the gene

Question 45

What are the 4 stages of the cell cycle

Answer 45

G1 S G2 M

Question 46

What does a gene consist of

Answer 46

All DNA sequences necessary to produce a single polypeptide or RNA product

Question 47

Simply, what is Transcription

Answer 47

DNA -> mRNA

Question 48

Simply, What is translation

Answer 48

mRNA -> Protein

Question 49

What 3 areas of a gene are unique to eukaryotic cells

Answer 49

Promoter region exons introns

Question 50

What is the genetic locus

Answer 50

A specific position or location on a chromosome

Question 51

What is an Allele

Answer 51

An alternate version of a DNA nucleotide sequence that may be t a given locus

Question 52

What is Diploid

Answer 52

Having maternal and paternal homologous chromosomes

Question 53

What is haploid

Answer 53

having only one of the two homologous chromosomes

Question 54

What is homozygous

Answer 54

Having the same alleys at a genetic sequence

Question 55

What is heterozygous

Answer 55

having different alleles at a genetic locus

Question 56

What is dominant

Answer 56

traits that are expressed in heterozygotes

Question 57

What are recessive traits

Answer 57

Traits that are expressed only in homozygotes