Topic 3 - Genetics

Question 1

Advantages of Sexual Reproduction

Answer 1

• Variation in offspring
• Better adapted
• Less disease

Question 2

Disadvantages of Sexual Reproduction

Answer 2

• Time and energy to find mate
• Not all will have mates to pass alleles

Question 3

Advantages of Asexual Reproduction

Answer 3

• Time and Energy efficient
• Quick

Question 4

Disadvantages of Asexual Reproduction

Answer 4

• More susceptible to disease

Question 5

Role of Meiosis

Answer 5

• To create genetically different gametes

Question 6

DNA

Answer 6

Polymer made of:
- 2 strands to form double helix
- Strands linked by complementary base pairs
- Weak hydrogen bonds between pairs
- Nucleotides with sugar and phosphate group with 1 base attached to sugar

Question 7

Genome

Answer 7

• Entire DNA

Question 8

Gene

Answer 8

• Section of DNA coded for specific characteristic

Question 9

Step 1 - DNA Extraction

Answer 9

• Mash fruit

Question 10

Step 2 - DNA Extraction

Answer 10

• Add detergent and salt

Question 11

Step 3 - DNA Extraction

Answer 11

• Filter

Question 12

Step 4 - DNA Extraction

Answer 12

• Add ice cold ethanol

Question 13

Genetic Variants in the NON-CODING DNA of a gene can affect phenotype by…

Answer 13

• changing the amount of protein produced

Question 14

Genetic Variants in the CODING DNA of a gene can affect phenotype by…

Answer 14

• changing the amino acid sequence and therefore the protein produced

Question 15

Transcription (first) phase of Protein Synthesis

Answer 15

1. DNA unwinds
2. RNA nucleotide line up along template strand using complementary base pairing to copy the code. T is replaced by U
3. mRNA forms and leaves the nucleus

Question 16

Translation (second) phase of Protein Synthesis

Answer 16

1. mRNA arrives at ribosome
2. tRNA brings over the corresponding anticodon
3. bond form between amino acids
4. The remaining amino acids fold on each other and form a protein

Question 17

What did Mendel’s work help discover?

Answer 17

• Selective Breeding
• Alleles separate during gamete formation (Law of Segregation)

Question 18

Why are there differences in the inherited characteristics as a result of alleles?

Answer 18

• Dominance and Recessiveness
• Multiple Alleles
• Mutation
• Environmental factors
• Random combinations during reproduction

Question 19

Allele

Answer 19

• Version of a gene which code for different versions of a characteristic

Question 20

Phenotype

Answer 20

• Physical observable characteristic

Question 21

Genotype

Answer 21

• Alleles that code for phenotype

Question 22

Dominant

Answer 22

• Allele which is always expressed in Genotype/Phenotype

Question 23

Recessive

Answer 23

• Allele only expressed if there are 2 of them

Question 24

Homozygous

Answer 24

• Two same alleles

Question 25

Heterozygous

Answer 25

- Two different alleles

Question 26

Chromosomes

Answer 26

- Structures in cells which carry DNA

Question 27

Monohybrid Inheritance

Answer 27

- Inheritance of characteristics controlled by a single gene

Question 28

Description of inheritance of the ABO blood groups with reference to multiple alleles and codominance

Answer 28

Multiple Alleles: - Determined by presence of 3 alleles: IA, IB and IO Codominance: - IA and IB are codominant, meaning if an individual inherits both alleles, they will express IAB allele

Question 29

How are sex-linked genetic disorders inherited?

Answer 29

Recessive disorders: >Males - Chromosomes X^r,Y will express disorder >Females - Chromosomes X^r,X^r will express disorder Dominant disorders: >Males - Chromosomes X^R,Y will express disorder >Females - At least one X^R (X^R,X^R or X^R,X^r) will express disorder

Question 29

Most phenotypic features are the result of:

Answer 29

multiple genes, not only 1

Question 29

Causes of variation:

Answer 29

Genetic: - Mutation and sexual reproduction Environmental: - An organisms' environment

Question 30

The Human Genome Project:

Answer 30

- Mapped entire human genetic code Allows for: - Genetic disorder testing - Personalised medication

Question 31

Genetic variation in a species are due to:

Answer 31

mutation

Question 32

Most genetic mutations have no affect on

Answer 32

phenotype