Chapter 17: Gene Expression Part 3

Question 1

Free ribosome

Answer 1

synthesize proteins that function in the cytosol, float freely in the cytoplasm

Question 2

Bound ribosome

Answer 2

make proteins of the endomembrane system and proteins that are secreted from the cell, in the rough ER

Question 3

Signal peptide

Answer 3

markers for polypeptides designed for the ER or secretion

Question 4

signal recognition particle (SRP)

Answer 4

binds to the signal peptides and escorts the ribosome to a receptor protein build into a ER membrane

Question 5

Mutations

Answer 5

changes in genetic information of a cell

Question 6

Point Mutations

Answer 6

changes in just one nucleotide pair of a gene

Question 7

Genetic disorder/hereditary disease

Answer 7

if a mutation has an adverse affect on a phenotype

Question 8

Nucleotide-pair substitution

Answer 8

One nucleotide pair is replaced with another pair of nucelotides

Question 9

Silent mutation

Answer 9

Have no effect on the amino acid produced by a coon because of redundancy in the genetic code

Question 10

Missense mutation

Answer 10

still codes for an amino acid, but not the correct amino acid

Question 11

Nonsense mutation

Answer 11

changes an amino acid codon into a stop codon; most lead to a nonfunctional protein

Question 12

Frameshift mutation

Answer 12

insertion or deletion of nucleotides that alters the reading frame (totally different triplet/codon resulting in totally different amino)

Question 13

Mutagens

Answer 13

physical or chemical agents that cause mutations, most carcinogens are mutagens, some mutagens are naturally occurring (like sunlight)

Question 14

What are the 2 types of small-scale mutations?

Answer 14

Substitutions: nucleotides are replaced by other nucelotide pairs, causing mutations

Insertions/deletions: gain or lose a nucleotide pair

Question 15

Discuss the evolution of a gene.

Answer 15

***A gene has evolved from being a unit of inheritance to a region of a specific nucleotide sequence in a chromosome to a DNA sequence that codes for a specific polypeptide chain.

We understood genes to be the reason we looks like our parents, to understanding why genes are unique (through their nucleotide sequences), to understanding that genes are nucleotide sequences attached to proteins with specific builds and specific functions that are unique to each protein. So DNA provides the blueprint for every cell in our body to work efficiently. A gene is a region of DNA that can be expressed to produce a final functional product that is either a protein or an RNA molecule

Question 16

Describe point mutations.

Answer 16

Point mutations are a change in the coding of DNA through a specific nucleotide pair. This mutations can occur through substitution, insertion, or deletion. Because there are several different codons for certain aminos, these mutations can be silent. Sometimes these mutations create stop codons, leading to a nonfunctional protein. Insertion and deletions are the addition or elimination of nucleotide pairs, causing a shift in the reading frame. This is detrimental to be polypeptide because it completely alters the amino acid sequence.