Molecular Genetics

Question 1

What are the two processes of gene expression?

Answer 1

a) Transcription and Translation

Question 2

Gene expression is the__________ of molecular biology

Answer 2

Central Dogma

Question 3

What is DNA Vs RNA?

Answer 3

DNA
-Nucleotides contain Deoxyribose sugar
-DNA bass are A T G and C
-Only found in the nucleus
-Antiparrallal cells
-DNA is a double stranded helix
RNA
-Neculotides contain ribose sugar
-the RNA bases are A U G C
-Found in the nucleus and cytoplasm
-strand is read in 5 to 3 direction

Question 4

There are three types of RNA but only one is used in transcription, what is it and what does it mean?

Answer 4

Messenger RNA: Varies in length, end product of transcription of a gene, moves to the ribosome.

Question 5

What are the steps for transcription? What is Transcription?

Answer 5

a) Initiation, Elongation, termination and post transcriptional modification.
b) Transcription involves synthesis of mRNA from a DNA template.

Question 6

What is the initiation process? of transcription

Answer 6

A transcription machine made out of RNA polymers is arranged on the template strand and binds to the promoter region, how you can indicate the location is by locating the TATA box. It shows the RNA polymers where to start and which DNA to transcribe. And the start codon is AUG, every DNA gene must begin with the complementary sequence to this (TAC)

Question 7

What is the elongation process? of Transcription

Answer 7

Transcription begins at the TAC sequence, RNA polymers adds bases at the 3 end which means mRNA is being made in the 5 to 3 direction.

Question 8

what is the ternimation process? of Transcription

Answer 8

specific DNA sigquence signal the end of transcription there are 3 stop codons so there are 3 DNA triplets.

Question 9

what is the post transcriptional modifications in transcriptions?

Answer 9

In prokaryotes mRNA can be used directly, in eukaryotes mRNA needs to be modified, the “raw” mRNA is a rough draft called primary transcript. It needs to be edited, by removing junk segments called introns and splicing together coding segments called exons. this is carried out by spliceosomes.

Question 10

what are the requirements for translation?

Answer 10

mRNA, ribosomes, tRNA and amino acids

Question 11

what are the three types of RNA?

Answer 11

1.mRNA, used in transcription. This is the linear sequence of bases which is read in groups of 3 bases called codons.
2. Transfer RNA, they transfer the amino acids from the cytoplasm to the ribosome, has 2 binding sites the anticodon and the amino acid binding site.
3.Ribosomal RNA, ribosomes are responsible for protein synthesis, composed of rRNA and proteins.

Question 12

what are the steps of translation?

Answer 12

1. Initiation, 2. Elongation, 3.Termination, 4. post translational modifications.

Question 13

What is the initiation process in translation>

Answer 13

Attaches mRNA to a ribosome, at the start codon, AUG means bring me methionine. You bring in the first amino acid, tRNA delivers the amino acid to the p site.

Question 14

what Is the elongation process in translation?

Answer 14

Brings in the second amino acid, and continues adding amino acids and creating protein.

Question 15

what is the ternimation in translation?

Answer 15

Process continues until the ribosome reaches the 3 stop codons. This causes the chain to be released, tRNA are released and mRNA is released and ribosome breaks apart.

Question 16

what is the post translational modification? in translation

Answer 16

Polypeptide goes to E.R and Golgi apparatus.

Question 17

What is the fate of the protein after translation?

Answer 17

May stay in the cell to be used locally, may be bundled into a vesicle for secretion into bloodstream, will exert an affect on cells to give rise to a genetic trait.

Question 18

what are mutations?

Answer 18

a permanent change in the nucleotide sequence of a cell’s DNA, can be passed onto daughter cells, typically neutral or harmful, rarely beneficial.

Question 19

what are the two types of mutations?

Answer 19

1.Somatic mutations which occur in somatic cells, passed during mitosis not to generations.
2. Germ-line mutations
occurs in cells that give rise to gametes, passed to generations.

Question 20

difference and similarities between gremlin mutations?

Answer 20

somatic
cannot be inherited, mutation like tumor

gremlin mutations
present in egg or sperm, can be inherited cause cancer family syndrome.

Question 21

Two causes of mutations.

Answer 21

1. Spontaneous
   - takes place naturally. During DNA replication, reposting of hydrogen bonds, slipped DNA
2. Induced
   -caused by agents outside the cells.
   Mutagen is a substance that increases the rate of mutation.

Question 22

examples of induced mutations:

Answer 22

-Nitrous acid,
can turn C in DNA into U

-Benzopyrene,
component of cigarette smoke: adds large chemical group to G making it unavailable for base pairing.

-Ionizing radiation
produces high reactive chemical species called free radicals which causes the bases in DNA to be unrecognizable.

Ultraviolet
-can cause adjacent thymines to bond together

Question 23

mutations can be categorized as:

Answer 23

A. Chromosomal- Large scale
B.Point mutations- small scale

Question 24

Point mutations

Answer 24

a) Base pair substitution
-The base pair G/T is replaced by an A/T pair

B) frameshift mutation
base pair is added or deleted.

Question 25

Base pair substitutions, three outcomes

Answer 25

I) silent mutations
II) missense mutations
iii) nonsense mutations

Question 26

what is the base pair substitution-silent mutation?

Answer 26

Codon is altered but due to redundancy in the code there is no change in the amino acid, the protein will not be affected.

Question 27

What is the base pair substitution for mis-sense mutations?

Answer 27

A codon is altered and a different amino acid is coded for, this can affect how the protein folds which can affect the function of the protein.

Question 28

What is the base pair subsitution-Non-sense mutations?

Answer 28

Codon is altered and becomes a stop codon, this makes the protein non functional

Question 29

What is the point mutation-Frameshift mutations?

Answer 29

Invoice the addition or deletion of a base causing the reading frame and this makes the protein useless.

Question 30

True or false: Mutations that occur in the exon of a gene tend to cause the largest problems while those in the non-coding regions of genes tend to be less severe?

Answer 30

TRUE

Question 31

what are the mechanisms of repair?

Answer 31

1.Proofreading, DNA polymerase I and DNA polymerase II proof-read and fix mistakes as new DNA is being made.