Lecture 16 Objectives

Question 1

What are the 3 parts of a nucleotide?

Answer 1

Phosphate, sugar, base

Question 2

How does deoxyribose differ from ribose?

Answer 2

Deoxyribose contains a hydrogen at carbon 2, less reactive, more stable

Ribose contains a hydroxyl group at carbon 2, more reactive, less stable

Question 3

What are the two types of nitrogenous bases?

Answer 3

Pyrimidine and purine

Question 4

Which bases are pyrimidines?

Answer 4

Cytosine, uracil, thymine

Question 5

Which bases are purines?

Answer 5

Adenine, guanine

Question 6

What is the difference between deoxyribonucleotides and ribonucleotides?

Answer 6

Deoxyribonucleotides - sugar:deoxyribose Base: adenine, guanine, cytosine, or thymine

Ribonucleotides - sugar: ribose base: adenine, guanine, cytosine, uracil

Question 7

What are the functions of nucleotides?

Answer 7

Components of many coenzymes, second messengers, serve as an energy source for biosynthetic reactions(ATP predominately)

Question 8

What type of bond links nucleotides?

Answer 8

Phosphodiester bond

Question 9

Where does the phosphodiester bond occur?

Answer 9

Between a phosphate and hydroxyl group

Question 10

What enzyme catalyzes the linkage of nucleotides?

Answer 10

DNA polymerase

Question 11

What is the primary structure of DNA and RNA?

Answer 11

Sequence of nucleotides built by DNA polymerase, sugar-phosphate backbone with nitrogenous bases extending from one side

Question 12

What is the secondary structure of DNA and RNA??

Answer 12

Pairing of the primary structure bands in a twisted double helix structure - antiparallel and complementary base pairing

Question 13

What is the tertiary structure of DNA?

Answer 13

Double helix wraps around proteins called histones, histone proteins assist in DNA compacting itself, forms a nucleosome (DNA and histone), nucleosomes are packaged into a fiber, called chromatin

Question 14

When do chromosomes form?

Answer 14

During cell division(mitosis) - chromatin fibers loop and coil again

Question 15

What are the 3 components of a chromosome?

Answer 15

Chromatid, centromere, telomere

Question 16

Where is DNA located?

Answer 16

In the cell nucleus and also mitochondria

Question 17

What is the function of DNA?

Answer 17

Store genetic information

Question 18

What is a genome?

Answer 18

Complete set of genetic instructions

Question 19

What is a gene?

Answer 19

Sections of DNA that contain instructions for a specific molecule, usually a protein

Question 20

What is an intron?

Answer 20

Non-protein coding sequences of DNA, controls gene expression, 95% of genome

Question 21

What is an exon?

Answer 21

Protein-coding sequences of DNA, controls gene expression - 5% of genome

Question 22

What is gene expression?

Answer 22

The process by which genetic instructions are used to synthesize gene products

Question 23

What 2 processes make up gene expression?

Answer 23

Transcription and translation

Question 24

What is transcription?

Answer 24

Making mRNA from DNA

Question 25

Where does transcription occur?

Answer 25

Nucleus

Question 26

What is the DNA template strand?

Answer 26

Antisense strand

Question 27

What is the DNA coding strand?

Answer 27

Sense strand

Question 28

What is the antisense strand?

Answer 28

The strand of DNA being transcribed by RNA polymerase

Question 29

What is the sense strand?

Answer 29

The strand of DNA not being transcribed into RNA

Question 30

How is chromatin regulated during gene expression? (3 steps)

Answer 30

``` -gene is switched on uncoiled chromatin histones are acetylated transcription begins reversible - gene is switched off Condensed chromatin Histones are deacetylated No transcription Reversible - methylation Combined with deacetylation No transcription Permanent ```

Question 31

Describe the process of transcription

Answer 31

- RNA polymerase unwinds - synthesizes a complementary RNA strand - elongation continues until a termination signal is reached

Question 32

In what direction is the DNAZ template read?

Answer 32

3' to 5'

Question 33

In what direction is RNA synthesize?

Answer 33

5' to 3'

Question 34

What is the function of the 5' cap?

Answer 34

Projects mRNA from degradation when traveling from nucleus to ribosome, permits efficient initiation of translation

Question 35

What is the function of the poly-A-tail?

Answer 35

Protects mRNA from degradation when traveling from nucleus to ribosome

Question 36

What post-translational modification occurs to mRNA?

Answer 36

Splicing

Question 37

What is splicing?

Answer 37

Removal of introns that do not code for proteins by spliceosomes

Question 38

What are spliceosomes?

Answer 38

Small nuclear RNAs that act as a catalase

Question 39

What enzyme synthesizes messenger RNA?

Answer 39

RNA polymerase II

Question 40

What percentage of RNA synthesized is mRNA?

Answer 40

5%

Question 41

What is the function of mRNA?

Answer 41

Carries genetic info from genes to ribosomes for protein synthesis (translation)

Question 42

What enzyme synthesizes transfer RNA?

Answer 42

RNA polymerase III

Question 43

What percentage of RNA synthesized is tRNA?

Answer 43

15% of RNA

Question 44

What is the function of tRNA?

Answer 44

Translated information in mRNA into sequences of amino acids

Question 45

What enzyme synthesizes ribosomal RNA?

Answer 45

RNA polymerase I

Question 46

What percentage of RNA synthesized is rRNA

Answer 46

80%

Question 47

What is the function of rRNA?

Answer 47

Components of ribosomes that carry out protein synthesis