Lecture 2

Question 1

Chromatin is viewed under the electron microscope as

Answer 1

Regularly beaded thread

Question 2

DNA is
Histones are

Answer 2

Acidic and -vely charged due to phosphate grps
Basic and +vely charged

Question 3

Histones are rich in
Contact the DNA through

Answer 3

Lysine and arganine
Minor groove

Question 4

Histones types

Answer 4

H1>phosphorylation during condensation, lysine rich
H2A >lysine rich
H2B> lysine rich
H3> arganine rich
H4> arganine rich

Question 5

Chemical modifications of histones

Answer 5

Acetylation during replication
Acetylation and methylation during transcription
ADP ribosylated during DNA repair

Question 6

A nucleosome

Answer 6

Histone octamer (H2A, H2B ,H3, H4)*2
1 3/4 toroidal supercoiled DNA
140bp
H1 attached to linker DNA

Question 7

Non histones
Interact wit-
Function
Types

Answer 7

Major groove
Regulation of gene expression, replication and transcription

Nucleoplasmin
Scaffold proteins
Enzymes
Regulatory proteins

Question 8

An anionic nuclear protein that interacts with histones
Function

Answer 8

Nucleoplasmin
Proper nucleosome assembly
Preventing nonspecific DNA and histone binding

Question 9

Why pack the DNA

Answer 9

to fit in the nucleus
Efficient replication
Genetic expression

Question 10

Centromere is rich in
Connected to…to form..where…

Answer 10

A–T
Specific proteins
Kinetochore complex
Spindle attaches

Question 11

Level 1 packing
Ratio
Diameter
What

Answer 11

Ratio 10
Diameter 10
10nm fibril
Nucleosomes

Question 12

Level 2 packing
Ratio
Diameter
What
requires

Answer 12

Ratio 50
30 nm diameter and fiber
Solenoid, cylindrical coil
1 solenoid is 6 nucleosomes
H1 histones

Question 13

Level 3 packing
Ratio
A rosette is
The

Answer 13

8000
Twisted loop+ scaffold proteins
1 rosette= 6 loops
Coil = 30 rossette
Chromatid 10 coils

Question 14

A gene is

Answer 14

Unit of DNA that encodes a particular protein
A seq of nucleotides on a DNA molecule

Question 15

Most eukaryotic genes are

Answer 15

Discontinuous
Exons coding and unique
Introns non coding and repetitive

Question 16

What is the use of introns

Answer 16

Eukaryotic versatility
Evolution and specialisation value
Variation

Question 17

Do all cells express the same exons

Answer 17

No each cell expresses different ones acc to its needs

Question 18

A chromosome has …..gene with locations called…

Answer 18

100s-1000s
Locus

Question 19

3 billion (3*10^9) bp is the
while 30k-50k is

Answer 19

Genome
number of genes

Question 20

Thymine in rna is

Answer 20

A minor base

Question 21

What is non coding rna

Answer 21

Small rna species found in eukaryotes includes
Small nuclear rna snrna»mRNA processing
Micro rna mirna»regulation of gene expression

Question 22

Can rna have h bonds

Answer 22

Yes sometimes it loops around itself and behaves like a double strand

Question 23

mRNA is… %
It is
Initiation
Termination

Answer 23

5
Heterogenous, varies in size and base seq
AUG
UAA,UAG,UGA

Question 24

Untranslated leader and tailing regions
Function

Answer 24

Transcribed with coding region present and mature mrna for
Mrna stability
Translational efficiency
Regulation of gene expression

Question 25

Monocistronic vs polycistronic

Answer 25

Monocistronic means only one gene with one initiation and one termination in eukaryotes Polycistronic more than 1 gene many initiation and termination Projaryotes

Question 26

Trna is the...abt... At least 1 specific... In prokaryotes... In eukaryotes... Mitochondria... ...%

Answer 26

Smallest 74-95 Amino acid 30 trna 50trna 22trna 15

Question 27

Trna contains an unusual base ... What causes it characteristic 2ndry and 3ry structure

Answer 27

Dihydrouracil Interchain base pairing, clover leaf appearance

Question 28

Acceptor arm D arm

Answer 28

Has CCA seq at the 3' hydroxyl end, carries amino acids as aminoacyl grps Has dihydrouracil, recognizes amino acyl synthetase enzyme that carries amino acids

Question 29

What does aminoacyl synthetase enzyme do

Answer 29

Catalyzes the binding of an amino acid to the trna

Question 30

Anticodon arm Extra arm

Answer 30

Has 3 bases that are an anticodon to the bases on the mrna,Help place each amino acid correctly into the peptide chain "adaptor" 3-12 bases, major site for variation in trna

Question 31

T¥C arm, loop IV

Answer 31

Has thymine and pseudo-uridine and cytosine after each other. C1' of ribose+ c5' of uracil (pseudo uracil) bind trna to the ribosome

Question 32

Ribosomal rna is ....% Prokaryotes it is... With subunits...and.. Eukaryotes it is... With subunits...and..

Answer 32

80 70S, 50S and 30S 80S , 60S and 40S

Question 33

The 60S subunit is formed of

Answer 33

5S RNA 5.8S RNA 28S RNA 49 proteins

Question 34

40S subunit is formed of

Answer 34

18S RNA 33 proteins

Question 35

The svedberg unit depends on

Answer 35

Molecular weight Particle size

Question 36

H1 histones can become H2A may become

Answer 36

phosphorylated during condensation linked to ubiquitin

Question 37

who is 140 bp? who is 60 bp?

Answer 37

nucleosome linker DNA

Question 38

telomeres contain

Answer 38

TTAGGG variable repeat number

Question 39

can same genotype can result in different phenotypes depending on the environment?

Answer 39

yes

Question 40

30S subunit contains 50 S

Answer 40

21 proteins and 16srRNA 34 proteins and 5S,33 S rRNA

Question 41

Non coding RNA

Answer 41

snRNA (mRNA processing) and miRNA (gene regulation)formed by RNAP-II in eukaryotes