DNA

Question 1

Define chromosome

Answer 1

A very long singular piece of DNA

Question 2

Define telomere

Answer 2

Specific DNA/protein structures found at both ends of chromosomes
TTAGGG

Question 3

Define centromere

Answer 3

Links the chromatids and consist of repetitive sequences

Question 4

Define Karyotype

Answer 4

Metaphase spread preparation
Chromosome number, sex complement, structural changes
E.g 46,XX

Question 5

Define homologous chromosome

Answer 5

A set of two sister chromosomes (one maternal and paternal) in a diploid organism with the same arm lengths and centrisome placement

Question 6

Define allele

Answer 6

An alternate form of a gene

Question 7

Define sister chromosome

Answer 7

Identical copies of a chromosome held together during DNA replication that remain attached until Anaphase

Question 8

Define diploid

Answer 8

2n
Two copies of each gene

Question 9

Define haploid

Answer 9

n
One copy of each gene

Question 10

Define aneuploidy

Answer 10

Condition of having an abnormal number of chromosomes in a haploid organism

Can be caused by non-disjunction during either meiosis or mitosis (failure to separate pairs of chromosomes lined up at the metaphase plate)

Question 11

Define germ cell

Answer 11

A cell containing half the number of chromosomes of a somatic cell and able to unite with one from the opposite sex to form a new individual/a gamete

Question 12

Define mutation

Answer 12

Any change in the DNA Sequence of a cell/ in the sequence of nucleotides that make up a gene
A heritable alteration in a gene or chromosome

Question 13

What is a point mutation

Answer 13

Change in the base pair code of a gene

Question 14

What is chromosomal mutation

Answer 14

Change in the structure or number of chromosomes in a cell

Question 15

What are transposons

Answer 15

Specific DNA sequences that can jump around the genome, contained within another molecule of DNA

They can inactivate genes or change their exoression

Question 16

What are SNPs

Answer 16

Single nucleotide polymorphism
Single base pair variation in a gene

Question 17

What are missense mutations

Answer 17

Change the amino acid code

Question 18

What are nonsense mutations

Answer 18

Lead to truncated proteins by coding for a early STOP codon

Question 19

Define autosomal

Answer 19

Gene in question is in a non-sex chromosome

Question 20

Define Translocation

Answer 20

Reciprocal swapping of a part of two chromosomes
Robertsonian translocation breaks at the centromere - can have no effect

Question 21

What is monosomy

Answer 21

Absense of one member of a pair of chromosomes
E.g turner syndrome

Question 22

What is trisomy

Answer 22

Presence of an additional chromosome
E.g Diwn syndrome

Question 23

What is polyploidy

Answer 23

The gain of an entire set of chromosomes
Becomes 3n
Can be caused by polyspermy

Question 24

What is a promoter

Answer 24

The region where proteins such as DNA Polymerase bind to initiate transcription

Question 25

What is a terminator

Answer 25

Section of the DNA strand that marks the end of a gene or Oberon during transcription

Question 26

Define transcription factors

Answer 26

A group of proteins that control the activity if genes through when they are turned off and on by binding to nearby DNA

Question 27

What is mismatch repair

Answer 27

Incorrect pair is incorporated and detected New DNA strand is cut, mispaired nucleotide and ones either side are removed Missing patch is replaced by DNA polymerase Ligase seals the backbone gap

Question 28

What is base excision repair

Answer 28

Deamination changes C to U U removed by Glycosylase Backbone remains intact Nucleotide is removed leaving a hole in the backbone Polymerase adds the correct nucleotide and ligase seals the backbone gap

Question 29

What is nucleotide excision repair

Answer 29

UV radiation produces a thymine dimmer Dimmer is detected and a DNA bubble forms around it (adjacent nucleotides hydrogen bonds break) Damaged region is cut out via enzymes DNA polymerase replaces the missing DNA using the template strand Ligase seals the gap

Question 30

Define Chromatid

Answer 30

One of the two halves of a chromosome that has been replicated during cell division

Question 31

Define intron

Answer 31

Contain regulatory elements (also junk DNA) Removed by splicing

Question 32

Define exon

Answer 32

Contain the coding sequence used to make proteins

Question 33

Define heterochromatin

Answer 33

Heavily condensed chromatin Genes not expressed

Question 34

Define euchromatin

Answer 34

Less condensed chromatin Genes are expressed