Genetics

Question 1

what does DNA stand for?

Answer 1

deoxyribonucleic acid

Question 2

name the four structures inside DNA

Answer 2

Adenine > Thymine

Guanine > Cytosine

Question 3

how many chromosomes does a person have?

Answer 3

46 chromosomes (23 pairs)

Question 4

explain replication

Answer 4

you have a strand of DNA. The enzyme helices cuts it down the middle and from this you can make new stands of DNA.
Primase starts the process - this enzyme makes a smaller piece of RNA (primer) which will be the starting point
Polymerase binds to the primer and makes a new strand.
Enzyme ligase seals the new DNA strand up

Question 5

explain transcription

Answer 5

instead of Thymine, Adenine pairs with Uriceil
when the gene gets ‘switched on’, RNA polymerase attaches to the strand of the DNA (one strand) it moves along the DNA making a strand out of the free bases in the nucleus. This creates mRNA

Question 6

explain translation

Answer 6

the mRNA (messenger RNA), moves out of the nucleus and into the cytoplasm
protein factories (ribosomes) bind to the mRNA and reads the code. It provides a chain made up of amino acids.
tRNA molecules carry the amino acids to the ribosomes.
the mRNA is read 3 bases at a time and the tRNA brings the right amino acid
This makes a chain of amino acids which then form a protein

Question 7

explain mitosis

Answer 7

occurs in somatic (non-reproductive) cells

produces cells with 23 pairs of chromosomes that are identical to the parent cell (diploid)

Question 8

explain meiosis

Answer 8

occurs in the gonadal tissue to produce gametes

produces daughter cells that have 23 chromosomes each (haploid)

Question 9

what is an allele?

Answer 9

most of the genome has two versions: one inherited from the mother and one from the father
is different versions of a sequence of DNA
alleles can be dominant (A)
alleles can be recessive (a)

Question 10

what is homozygous?

Answer 10

if both versions of allele are identical

Question 11

what is heterozygous?

Answer 11

if the versions of allele are different

Question 12

what is hemizygous?

Answer 12

if there is only one copy of allele

Question 13

what is a genotype?

Answer 13

your DNA code for that particular trait

Question 14

what is a phenotype?

Answer 14

the observational characteristic or trait - the genotype plus the effects of the environment

Question 15

in inheritance - what is autosomal dominant?

Answer 15

50% chance of passing the condition onto children
males and females equally effected
male to male transmission

Question 16

in inheritance - what is autosomal recessive?

Answer 16

parents of affected individuals are (usually) unaffected carriers
male and females equally affected
1 in 4 risk

Question 17

in inheritance - what is x-linked recessive

Answer 17

carrier females have a 50% chance of having an effected male
carrier females and affected males
no male to male transmission

Question 18

what is diploid?

Answer 18

a cell or a nucleus having 2 sets of chromosomes (pair)

Question 19

what is diploid?

Answer 19

a cell or a nucleus having a single set of unpaired chromosomes

Question 20

what are homologous chromosomes?

Answer 20

the cell has two sets of each chromosomes, one pair from the mother and one pair from the farther

Question 21

what is a karyotype?

Answer 21

number and appearance of chromosomes in the nucleus

Question 22

what are the first 22 chromosomes called?

Answer 22

autosomes

Question 23

what is the final pair (23) of the chromosomes called?

Answer 23

the ‘sex-chromosome’

Question 24

what is telomere?

Answer 24

the structure that seals the chromosomes

Question 25

what is mutation?

Answer 25

a permanent alteration of the nucleotide sequence of the genome

Question 26

what is mutagen?

Answer 26

a physical or chemical agent that changes the genetic material