Unit 2 Section 2- Genetics

Question 1

What bonds form between the complementary nucleotide base pairs?

Answer 1

Hydrogen bonds

Question 2

What are the advantages of the structure of DNA?

Answer 2

Double helix is very stable
Strong sugar phosphate backbone
Nucleotide bases on inside to protect from mistakes when copying
Molecules are long and tightly coiled up= genetic info can fit into small space
DNA molecules have a paired structure which makes it easier to copy itself- self replication is important for cell division

Question 3

What is a nucleotide made up of?

Answer 3

Phosphate, pentose/deoxyribose sugar and nucleotide/nitrogenous base

Question 4

How is nature and development determined by genes?

Answer 4

DNA determines amino acid sequence which codes for proteins. Proteins and enzymes formed, enzymes control metabolic pathways which determine growth and development.

Question 5

What is an allele?

Answer 5

Different versions of a gene

Question 6

What is the gene locus?

Answer 6

The position of a gene

Question 7

What is a mutation?

Answer 7

A change in the DNA base sequence

Question 8

How can a mutation cause a non functional enzyme?

Answer 8

Mutation in DNA sequence results in different amino acid sequence, protein may not fold properly, wrong shaped active site, enzyme substrate complex unable to form

Question 9

What is the name of the cell when gametes fuse?

Answer 9

Zygote

Question 10

What does haploid mean?

Answer 10

In gametes the number of chromosomes is half that of a normal cell so that once gametes combine the cell has a normal diploid number of chromosomes

Question 11

What is genetic diversity?

Answer 11

The more variety within a species the more genetically diverse it is. Variety is due to different alleles in the population.

Question 12

Why does DNA within a species vary very little?

Answer 12

All members within a species have the same genes

Question 13

How is genetic diversity within a population increased?

Answer 13

Mutations in DNA can form new alleles

Gene flow when individuals from another population migrate into them and reproduce introducing new alleles

Question 14

What is the gene pool?

Answer 14

The gene pool is the complete range of alleles in the population

Question 15

What factors can decrease genetic diversity?

Answer 15

Genetic bottleneck
Founder effect
Selective breeding

Question 16

What is a genetic bottleneck?

Answer 16

An event causes a big reduction in the population- organisms die before reproducing
This reduces the number of different alleles in the gene pool so reduces genetic diversity
The survivors reproduce and a larger population is created from a few individuals
The genetic diversity of the new population remains restricted

Question 17

What is the founder effect?

Answer 17

Few organisms from a population start a new colony
Only a small number of individuals contribute alleles (small fraction of alleles of the population as a whole) to gene pool= genetic diversity reduced
More inbreeding in the new population= higher incidence of genetic disease as the limited genetic diversity means they are less able to adapt

Question 18

Why is reduced genetic diversity not advantageous?

Answer 18

Less diversity means fewer alleles therefore the population are less able to adapt to change in conditions/environment

Question 19

What is selective breeding?

Answer 19

Individuals with desired characteristics are bred together
Offspring with desired characteristics bred together
Continues over many generations until a population all have desired characteristics but reduced genetic diversity