BIOL 115 Exam 2

Question 1

Base substitution- what are the two types and how do they work?

Answer 1

Changes the base of a single DNA nucleotide

Two types:
- Transitions
-Transversions
Replaced with different bases
Pyrine (T replaced with Purine (A) and Purine (A) replaced with Pyrine (T)

Question 2

Transition

Answer 2

Replaced by the same base

(Pyrine (T) to Pyrine (C) and a Purine (A) to a Purine (G)

Question 3

Transversions

Answer 3

Replaced with different bases

Pyrine (T replaced with Purine (A) and Purine (A) replaced with Pyrine (T)

Question 4

3 major types of mutations?

Answer 4

Base substation, Insertions and Deletions, and Expanding Nucleotide Repeats

Question 5

Insertion

Answer 5

Extra base or bases is added to the DNA strand causing a frameshift

Question 6

Deletion

Answer 6

Base or bases are removed from DNA strand causing a frame shift

Question 7

Frameshift Mutation

Answer 7

Caused by insertion or deletion that alters the reading frame of a gene (can be bad which affects amino acids and mRNA)

Question 8

In-Frame Insertions and Deletions

Answer 8

caused by insertions and deletions of a multiple of 3 nucleotides (this leaves frame intact even though there was an insertion or deletion which effects the phenotype) but does NOT alter the reading frame

Question 9

Expanding Nucleotide Repeats - what is it and what if there is too many?

Answer 9

Repeated sequence of a set of nucleautides casing number of copies of the sequence to increase

If too many…
Causes a disease to form

Question 10

What mutation effects phenotypes?

Answer 10

Forward Muation and Reverse Mutation

Question 11

Forward Mutation

Answer 11

Changes wild-type phenotype to a phenotype that is ‘mutant’

Question 12

Reverse Mutation

Answer 12

Changes a ‘mutant’ phenotype back to the ‘wild type’ phenotype

Question 13

Wild type phenotype

Answer 13

An individual having the normal phenotype; that is, the phenotype generally found in a natural population of organisms

Question 14

Mutant Phenotype

Answer 14

An individual has a phenotype that differs from the normal phenotype. Occurs by natural selection or crossing over with a different species of the same gene

Question 15

What mutations effect the Protein Structure?

Answer 15

Missense mutation, nonsense mutation, and silent mutation

Question 16

Missense Mutation- what causes it and what are the different conditions?

Answer 16

Overall: caused by Transition and transversion from base substitution

1) When a single nucleotide base in a DNA sequence is swapped for another one, resulting in a different codon and, therefore, a different amino acid.

ex: TTC-> TCC (Pyrine to Pyrine) TRANSITION
causing Protein to be: Conservative

2) If the amino acid substitution involves two amino acids with very different chemical properties which causes changes in protein:

ex: TTC-> TGC (Pyine to Purine) TRANSEVERSION
causing protein to be: Non-conservative

Protein Changes:
Conservative - Protein is functional
Non-conservative - Protein is not functional

Question 17

Nonsence

Answer 17

The amino acid is replaced with a stop codon (seen in mRNA) which signals the ribosome to stop building a protein

ex: TAG -> UAG
Examples of STOP codons: UAA, UAG, and UGA

Question 18

Silent Mutation

Answer 18

The substitution doesn’t change the amino acid that the codon codes for
ex: AAA-> AAA

Question 19

Neutral Mutation

Answer 19

Changes the amino acid sequence of a protein without altering its ability to function

Question 20

Loss-of-function Mutation

Answer 20

Causes a complete or partial loss of function
Affects; structure of protein, transcription and translation

Question 21

Gain-of-function Mutation

Answer 21

Causes the appearance of a new trait or function
or
causes the appearance of a trait in inappropriate tissue or at an inappropriate time

Question 22

Lethal Mutation

Answer 22

Causes premature death

Question 23

Conditional Mutation

Answer 23

Expressed only under certain mutations that affect phenotype at elevated temperatures

Question 24

Suppressor Mutation and what are the two classes?

Answer 24

Suppresses the effect of an earlier mutation at a different site

2 classes of suppressor mutation:
Intragenic and Intergenic

Question 25

Intragenic Supressor Mutation

Answer 25

Suppresses the effect of an earlier mutation within the SAME gene

ex: can suppress a frameshift mutation

Question 26

Intergenic Suppressor Mutation

Answer 26

Suppresses the effect of an earlier mutation in a DIFFERENT gene

ex: translation can occur even with a stop codon

Question 27

Genotype

Answer 27

Organisms Genetic Information (alles passed by the parent)

ex: BB, Bb, or bb

Question 28

Phenotype

Answer 28

The appearance of a character (Observable traits)
- It is influenced by the genotype

ex: purple, white, wrinkled, round…

Question 29

Locus

Answer 29

Stripe on the chromosomes ( specific physical location of a gene)

ex: Each chromosome has an allele (one white flower and the other for the purple flower)

Question 30

Heterozygote

Answer 30

Inherit a different version of a gene from each parent. They do not match

ex: Bb and bB

Question 31

Homozygote

Answer 31

Inherit the same version of the gene from each parent, so you have two matching genes

ex: BB and bb

Question 32

Diploid

Answer 32

Two copies of each chromosome (most organisms)

ex: in a pair (2-2-2)

Question 33

Haploid

Answer 33

One copy of each chromosome (in most gametes like sperm or eggs)

ex: single (1-1-1)

Question 34

Characteristic

Answer 34

Feature of an organism

Ex: Seed shape

Question 35

Allele

Answer 35

Only one of two or more alternative forms of a gene

ex: R (dominant) and r (recessive)