Topic 6 - Inheritance, Variation and Evolution

Question 1

What does DNA stand for?

Answer 1

Deoxyribonucleic acid

Question 2

What is DNA?

Answer 2

A double stranded polymer that forms a double helix. It contains genetic material.

Question 3

What is a gene?

Answer 3

A gene is a small section if DNA found in a chromosome

Question 4

Where is DNA found?

Answer 4

In chromosomes

Question 5

What is a genome?

Answer 5

A genome is the entire set of genetic material in an organism.
Scientists have worked out the human genome.

Question 6

What are three benefits for understanding the human genome?

Answer 6

1. It allows scientists to identify genes that are linked to disease
2. Allow scientists to develop and understand drugs that effect genetic diseases
3. The genome can be used to trace migration patterns of certain population as when people migrate they develop small changes and adaptations within their genome.

Question 7

What is the name of the monomer DNA is made from?

Answer 7

A nucleotide

Question 8

What three things does a nucleotide consist of?

Answer 8

1. Phosphate
2. Sugar
3. Base

Question 9

What are the four possible bases in DNA?

Answer 9

A,T,C,G

Question 10

Which bases are complimentary to each other?

Answer 10

A and T
C and G

Question 11

What is mRNA?

Answer 11

mRNA or a template is a single stranded copy of DNA used to transport genetic code through the cytoplasm.

Question 12

What structure is DNA?

Answer 12

Double Helix Structure

Question 13

Where does protein synthesis take place?

Answer 13

Ribosomes

Question 14

How are proteins made?

Answer 14

Proteins are made from amino acids. They are made of amino acids. mRNA is used to transport the code and order of amino acids to the ribosome.

Question 15

What are three uses of proteins?

Answer 15

1. Enzymes - biological catalysts that speed up reactions
2. Hormones - used to carry messages around the body
3. Structural proteins - physically strong

Question 16

What is a codon?

Answer 16

A codon us a sequence of three bases that codes for one amino acid.

Question 17

How many amino acids are there?

Answer 17

20

Question 18

What is a mutation?

Answer 18

A mutation is the change in the sequence if DNA resulting in a genetic variant. Mutations happen continuously

Question 19

What can a mutation lead to?

Answer 19

Mutations don’t often cause major changes only small changes in appearance however they can lead to changes in the amino acid and sometimes changes in the protein?

Question 20

With an enzyme as an example, why is a mutation of a protein bad?

Answer 20

If a enzyme is mutated it may have a different active site, this means it cannot bind to a substrate and cannot do it’s job

Question 21

What are the three types of mutations?

Answer 21

Insertions
Deletions
Substitutions

Question 22

Explain the mutation of insertion?

Answer 22

Insertion is the addition of a new base into the DNA sequence
- an insertion changes the way a sequence is read so can change the amino acid hey code for.
- insertions can cause a knock on effect.
E.g.
TAT-AGT-CTT
Addition if G
TAT-AGG-TCT-T

Question 23

Explain the mutation of Deletions?

Answer 23

A deletion is when a random base is deleted from the DNA sequence.
Like insertions they change the way the sequence is read and can cause a knock on effect.

Question 24

Explain the mutation of substitutions?

Answer 24

Substitutions are a random change from one base to another.
Substitutions change the way the sequence is read but will not cause a knock on effect.

Question 25

What do X and Y chromosomes decide?

Answer 25

Your sex

Question 26

How many pairs of chromosomes does a human have?

Answer 26

23

Question 27

What chromosomes makes a male and female?

Answer 27

Male - XY
Female - XX

Question 28

What is an allele?

Answer 28

An allele is a different variation of the same gene

Question 29

How many alleles do you have per gene in your body?

Answer 29

Two - one on each chromosome pair

Question 30

What is a dominant allele?

Answer 30

An allele that controls the development of a characteristic even when only one is present

Question 31

What is a recessive allele?

Answer 31

A allele that controls the development of a characteristic but only when two are present because it can be overruled by the dominant allele.

Question 32

What does homozygous mean?

Answer 32

A gene is homozygous when it gas two alleles that are the same. A gene can be homozygous dominant or recessive

Question 33

What does heterozygous mean?

Answer 33

A gene is heterozygous when it’s alleles are different

Question 34

What does genotype mean?

Answer 34

Your genotype is the combination of alleles in a gene. This is written in letters e.g Aa or AA

Question 35

What does phenotype mean?

Answer 35

Phenotype is the characteristic that appears from the genotype.

Question 36

What is cystic Fibrosis ?

Answer 36

Cystic Fibrosis effects cell membranes and results in the body producing thick sticky mucus in the lungs and pancreas.

Question 37

What causes Cystic Fibrosis?

Answer 37

Cystic fibrosis is a recessive disease and is caused by two recessive alleles. Because it is recessive people with one copy will not be effected - they are known as carriers.

Question 38

What is polydactyls?

Answer 38

Polydactyly is a genetic disorder that cause a baby to be born with extra fingers or toes.

Question 39

What causes polydactyly?

Answer 39

A genetic disease caused by a dominant allele so it can be inherited by just one parent.

Question 40

How can embryos be screened for genetic disorders?

Answer 40

During IVF embryos are fertilised in a lab.
Before implantation a cell can be removed from the embryo and can be analysed genetic disorders.