Week 7-genes

Question 1

What are the 4 phases of a cell cycle?

Answer 1

1. First gap phase (G1)
2. Synthesis phase (S)
3. Second gap phase (G2)
4. Mitosis

Question 2

What are the 4 phases of mitosis?

Answer 2

1. Prophase
2. Metaphase - chromosomes align
3. Anaphase- move towards opposite ends of the cell
4. Telophase - Nucleus forms on each side, chromosomes return to random cell structure

Question 3

There are 2 different types of cell division, what are they?

Answer 3

1. Meiosis- cell division to produce gametes (sperm and egg cells)
2. Mitosis + cytokinesis - reproduction/division of other body cells (somatic)

Question 4

What are the 3 components of DNA?

Answer 4

1. Deoxyribose
2. Phosphate molecule
3. 4 types of nitrogenous bases (cytosine, thymine {pyrimidines}, adenine and guanine {purines}

Question 5

When does copying or replication occur in DNA?

Answer 5

The ‘s’ phase. It consists of breaking the weak hydrogen bonds between the bases, leaving a single strand with each base unpaired.

Question 6

What is complement pairing?

Answer 6

The consistent pairing of adenine with thymine and guanine with cytosine. This is accurate base pairing.

Question 7

How is the message from the nucleus to the cytoplasm transmitted in order for correct protein production?

Answer 7

1. Transcription-copying of DNA into a message that can leave the nucleus
2. Translation- conversion of the nucleic acid code into amino acid code
   This is mediated by ribonucleic acid (RNA)

Question 8

Where is the site of protein production?

Answer 8

The ribosome. Equal parts protein and RNA

Question 9

What are alleles?

Answer 9

Pairs or series of genes on a chromosome that determines the hereditary characteristics. Eg. Hair color

Question 10

What’s the difference between a genotype and a phenotype?

Answer 10

Genotype-genetic composition of a person.

Phenotype- characteristics and physical features

Question 11

What are dominant vs recessive genes?

Answer 11

Dominant- allele whose effects are observable

Recessive- allele whose effects are hidden

Question 12

What is a missense mutation?

Answer 12

Change in DNA base pair, that results in the substitution of one amino acid for another in the protein made by a gene

Question 13

What is a nonsense mutation?

Answer 13

A change in one DNA pair. The altered DNA sequence prematurely signals the cell to stop building a protein. This results in a shortened protein

Question 14

What is insertion mutation?

Answer 14

Changes the number of DNA bases by adding a piece of DNA

Question 15

What is deletion mutation?

Answer 15

Changes the number of DNA bases by removing a piece of DNA

Question 16

What is duplication mutation?

Answer 16

Abnormally copied DNA one or more times

Question 17

What is frameshift DNA?

Answer 17

The addition or loss of DNA bases changes a genes reading frame

Question 18

What is repeat expansion mutation?

Answer 18

Nucleotide repeats are short DNA sequences that are repeated a number of times in a row

Question 19

What is point mutation?

Answer 19

Refers to a single base insertion or deletion

Question 20

What is silent mutation?

Answer 20

Occurs when the deleted or inserted base has no influence on the final protein then that protein in dysfunctional

Question 21

What happens when a mutated allele in on a NONsex chromosome vs a sex chromosome?

Answer 21

NONsex- autosomal disorder

Sex- x linked/y linked disorder

Question 22

How many copies of the affected (dominant) allele is required for a person to have the disorder inherited, vs the recessive allele?

Answer 22

They only need one copy in dominant. A person has a 50% chance of inheriting the affected allele.
For inheritance of a recessive allele, the person needs both copies, one from each carrier

Question 23

When do chromosome abnormalities occur?

Answer 23

During meiosis (a single cells divides twice to produce 4 cells containing half the original amount of genetic information); it is more common in females.

Question 24

What is the process of the chromosome fails to separate?

Answer 24

It migrates as a pair which will produce gametes with abnormal numbers of a particular chromosome. It can be known as non-disjunction. Eg offspring may have 3 copies or one copy

Question 25

What are 2 chromosome abnormalities?

Answer 25

1. Turners syndrome- people have a single X chromosome. Women are infertile, sexually immature appearance and failed puberty
2. Klinefelters syndrome- x2 X chromosomes and x1 y. Men are infertile, have small testes and no sperm production

Question 26

Name some autosomal dominant disorders

Answer 26

• collagen disorders; most commonly marfans syndrome
• Huntington’s disease
• myotonic dystrophy

Question 27

What is the most common autosomal recessive disorder?

Answer 27

Cystic fibrosis

Question 28

What is the most well recognized sex linked, X linked recessive disease?

Answer 28

Hemophilia- a mutation in the gene coding for one of the factors in the clotting cascade

Question 29

Name an x linked disorder that results in intellectual disability?

Answer 29

Fragile x syndrome- the chromosome is damaged and has a ‘fragile’ appearance. It shows in strange facial structure, disability and behavioral issues.

Question 30

What are the agents called that interrupt fetal development?

Answer 30

Teratogens; drugs, chemicals, infectious agents etc