3.1 Genes

Question 1

Genome (definition)

Answer 1

the whole of the genetic information of an organism

Question 2

Gene (definition)

Answer 2

a heritable factor that consists of a length of DNA and influences a specific characteristic
- Genes encode a general characteristic (eye color)

Question 3

Allele (definition)

Answer 3

the various specific forms of a gene that usually vary from each other by one or a few bases
- Alleles encode for specific alternatives (blue eyes)

Question 4

Homozygous vs. Heterozygous

Answer 4

Homozygous - having two copies of the same allele
Heterozygous - having two different alleles

Question 5

Genotype vs. Phenotype

Answer 5

Genotype - The alleles you have for a gene
Phenotype - The trait you have as a result of your alleles

Question 6

Gene locus

Answer 6

the specific position of a gene on a chromosome

Question 7

Diploid State vs. Haploid State

Answer 7

Diploid State - having a pair of each kind of chromosome
Haploid State- having one copy of each

Question 8

Gene Mutation

Answer 8

a change in the nucleotide sequence of a section of DNA (gene) that encodes for a specific trait
- Change in gene sequence may alter the polypeptide sequence, leading to alternative forms of a protein
- The alternative forms may result in new functionalities or abrogate normal activity

Question 9

Causes for Mutations

Answer 9

Error in DNA relocation mechanisms
Exposure to radiation
Exposure to some chemicals

Question 10

Somatic Mutations

Answer 10

Occur in a single body cell and cannot be inherited (only tissue derived from the mutated cell are affected)

Question 11

Germline Mutations

Answer 11

Occur in sex cells (gametes) and can be passed on to offspring (every cell in the entire organism will be affected)

Question 12

What Mutations Do

Answer 12

Can causes bases to be deleted from or added to the DNA sequence
Can cause a different nitrogenous base to be used in a particular place
Can cause tumorigenesis

Question 13

Base-substitution mutation

Answer 13

a mutation that changes one nitrogenous base in a sequence
- Occur during DNA replication

Question 14

Mutagens

Answer 14

an agent that induces a permanent change to the genetic material of an organism (increasing the frequency of mutations above the natural background level)

Question 15

Three Types of Mutagens

Answer 15

Physical - certain forms of radiation including X-rays and ultraviolet (UV) light
Chemical - substances such as reactive oxygen species, certain metals and alkylating agents
Biological - come viruses and certain bacteria can induce mutations

Question 16

Silent Mutations

Answer 16

occur when DNA change does not alter the amino acid sequence of the polypeptide
(no change to the polypeptide sequence)

Question 17

Missense Muations

Answer 17

occur when the DNA change alsters a single amino acid in the polypeptide chain
(a single amino acid is changed in the polypeptide)

Question 18

Nonsense Mutations

Answer 18

occur when the DNA change creates a premature stop coon which truncates the polypeptide
(A stop codon is created, truncating the polypeptide)

Question 19

Frameshift Mutations

Answer 19

mutations involved in either the addition of removal of s single base of DNA changing the reading frame

Question 20

Sickle Cell Anemia (Mutation Consequence)

Answer 20

The amino acid change (Glu-> Val) alters the structure of the beta chain, making hemoglobin form insoluble strands
These insoluble strands change the shape of the red blood cell, causing it to form a sickle shape
The red blood cells cannot carry oxygen as effectively and are destroyed at a higher rate - leading to anemia
Sickle cells are also more likely to form damaging clots
- Missense mutation, single nucleotide change that lead to amino acid change