3 Genes

Question 1

Define Locus

Answer 1

Location of a gene on a chromosome

Question 2

What is a missense mutation

Answer 2

Benificial mutation - causes a new protein to form creating variation

Question 3

What is a silent mutation

Answer 3

A neutral mutation which causes no change to the proteins formed

Question 4

What is a nonsense mutation

Answer 4

A detrimental mutation which leads to no the protein building to stop

Question 5

What causes sickle cell anemia

Answer 5

A change to the 6th codon of the beta chain of haemoglobin causing a different shaped haemoglobin molecule
DNA - GAG to GTG (non transcribed strand)

Question 6

What amino acid changes in sickle cell anaemia

Answer 6

Glu to Val

Question 7

What structure is haemoglobin with sickle cell anaemia

Answer 7

Insoluble Fibrous Strands

Question 8

What are the possible effects of sickle cells

Answer 8

Clots in the capillaries due to sickle shape
Destroyed rapidly - anaemia due to low red blood cell count
Insoluble haemoglobin is less efficient - lethargy

Question 9

Define aneuploidy

Answer 9

abnormal number of chromosomes in a haploid set

Question 10

Define pseudogenes

Answer 10

Non-functional segments of DNA that resemble functional genes

Question 11

Describe bacterial conjugation

Answer 11

A donor cell replicates it’s plasmid and passes it to a recipient cell via it’s sex pili by creating a conjugation bridge

Question 12

Describe a nucleosome

Answer 12

8 histone proteins with DNA wrapped around

Question 13

Describe Chromatosomes

Answer 13

A string of nucleosomes connected by an additional histone protein

Question 14

Describe a solenoid

Answer 14

A ring of about 6 chromatosomes per turn which condenses to form 30nm fibre

Question 15

What are homologous pairs?

Answer 15

Name given to the pair of chromosomes with the same loci and structure, one maternal and one paternal

Question 16

When must homologous pairs be seperated?

Answer 16

Meiosis

Question 17

Define diploid

Answer 17

Cells with homologous pairs (two sets) of chromosomes (somatic cells)

Question 18

Define haploid

Answer 18

Cells with only one set of chromosomes (gametes)

Question 19

Why must gametes be haploid?

Answer 19

So two can fuse to form a diploid zygote

Question 20

Define Somatic cell

Answer 20

Diploid body cells

Question 21

Define heterosome

Answer 21

Sex chromosome

Question 22

Define autosome

Answer 22

Non sex chromosome (other 22 pairs)

Question 23

Which gene has the male characteristics?

Answer 23

SRY on Y chromosome

Question 24

What is a karyotype

Answer 24

The number and type of chromosomes in a eukaryote

Question 25

Define aneuploidies

Answer 25

When an organism has missing or additional chromosomes

Question 26

Define translocations

Answer 26

Chromosomes break and re-attach to another (chromosomal disorder)

Question 27

Define karyotyping

Answer 27

Using visual profiles called kariograms to determine chromosomal properties such as gender or identify disorders

Question 28

Define a non-disjunction event

Answer 28

This refers to the chromosomes failing to separate correctly, resulting in gametes with one extra, or one missing, chromosome

Question 29

Define Germline cells

Answer 29

Cells that divide into 4 genetically distinct gametes (egg/sperm cells)

Question 30

What is Mendel's First Law?

Answer 30

Law of segregation Each gamete carries only one allele for each gene (they are seperated)

Question 31

What is Mendel's Second Law?

Answer 31

Law of Independent Assortment The segregation of alleles for one gene is separate from any other gene

Question 32

What is Mendel's Third Law?

Answer 32

Principle of Dominance Recessive alleles will be masked by dominant alleles

Question 33

What zygosity is the sex chromosome in males?

Answer 33

Hemizygous

Question 34

What are the two possible genotypes for any given gene?

Answer 34

Heterozygous or homozygous

Question 35

Define phenotype

Answer 35

Physical characteristics

Question 36

Describe co-dominant alleles

Answer 36

Alleles can both impact on phenotype

Question 37

Define Mutagens

Answer 37

External factors that increase the rate of mutation (leading to genetic disease)

Question 38

Define Carcinogens

Answer 38

Mutagens that cause cancer

Question 39

Give an example of a biological agent which is a carcinogen

Answer 39

HPV virus

Question 40

What kind of gel is used to separate DNA?

Answer 40

Agarose

Question 41

What kind of gel is used to separate proteins?

Answer 41

Polyacrylamide

Question 42

What are proteins treated with before gel electrophoresis to linearize them and uniformize a negative charge?

Answer 42

Anionic detergent

Question 43

What name is given to the main genetic material in a prokaryote?

Answer 43

Genophore

Question 44

When does crossing over occur?

Answer 44

Prophase I

Question 45

What occurs in Meiosis I

Answer 45

Homologous pairs split

Question 46

What occurs in Meiosis II

Answer 46

Sister chromatids split

Question 47

Describe the process of crossing over

Answer 47

Non sister chromatids are held together at a chiasma The homologous chromosomes condense into a bivalent The bivalent is separated by meiosis creating recombinants

Question 48

Which factors increase genetic variability?

Answer 48

Crossing over Random assortment Random selection

Question 49

What are the two ways to genetically test foetuses?

Answer 49

Chronic villi sampling Amniocentesis

Question 50

Features of chronic villi sampling?

Answer 50

More dangerous Younger foetus

Question 51

Features of amniocentesis?

Answer 51

Less dangerous Older foetus

Question 52

Name an autosomal recessive disorder

Answer 52

Cystic fibrosis

Question 53

Name an autosomal dominant disorder

Answer 53

Huntington's

Question 54

What does it mean if genes are linked?

Answer 54

They are on the same chromosome

Question 55

Describe 3 categories of mutagens?

Answer 55

Radiation Chemical Biological agents

Question 56

Why can STRs be used for DNA profiling?

Answer 56

Short tandem repeats are usually unique to each individual They are cut with restriction enzymes and gel electrophoresis is undergone to compare results

Question 57

Describe somatic nuclear transfers

Answer 57

The nucleus is removed from an adult skin cell and transferred into an enucleated (nucleus removed) egg This is then implanted in the womb

Question 58

Give 4 examples of natural cloning

Answer 58

Binary fission Budding Fragmentation Identical twins