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Molecular > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

Chromatin is viewed under the electron microscope as

A

Regularly beaded thread

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2
Q

DNA is
Histones are

A

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

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3
Q

Histones are rich in
Contact the DNA through

A

Lysine and arganine
Minor groove

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4
Q

Histones types

A

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

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5
Q

Chemical modifications of histones

A

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

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6
Q

A nucleosome

A

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

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7
Q

Non histones
Interact wit-
Function
Types

A

Major groove
Regulation of gene expression, replication and transcription

Nucleoplasmin
Scaffold proteins
Enzymes
Regulatory proteins

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8
Q

An anionic nuclear protein that interacts with histones
Function

A

Nucleoplasmin
Proper nucleosome assembly
Preventing nonspecific DNA and histone binding

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9
Q

Why pack the DNA

A

to fit in the nucleus
Efficient replication
Genetic expression

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10
Q

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

A

A–T
Specific proteins
Kinetochore complex
Spindle attaches

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11
Q

Level 1 packing
Ratio
Diameter
What

A

Ratio 10
Diameter 10
10nm fibril
Nucleosomes

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12
Q

Level 2 packing
Ratio
Diameter
What
requires

A

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

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13
Q

Level 3 packing
Ratio
A rosette is
The

A

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

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14
Q

A gene is

A

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

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15
Q

Most eukaryotic genes are

A

Discontinuous
Exons coding and unique
Introns non coding and repetitive

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16
Q

What is the use of introns

A

Eukaryotic versatility
Evolution and specialisation value
Variation

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17
Q

Do all cells express the same exons

A

No each cell expresses different ones acc to its needs

18
Q

A chromosome has …..gene with locations called…

A

100s-1000s
Locus

19
Q

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

A

Genome
number of genes

20
Q

Thymine in rna is

A

A minor base

21
Q

What is non coding rna

A

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

22
Q

Can rna have h bonds

A

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

23
Q

mRNA is… %
It is
Initiation
Termination

A

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

24
Q

Untranslated leader and tailing regions
Function

A

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

25
Q

Monocistronic vs polycistronic

A

Monocistronic means only one gene with one initiation and one termination in eukaryotes

Polycistronic more than 1 gene many initiation and termination
Projaryotes

26
Q

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

A

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

27
Q

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

A

Dihydrouracil
Interchain base pairing, clover leaf appearance

28
Q

Acceptor arm
D arm

A

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

29
Q

What does aminoacyl synthetase enzyme do

A

Catalyzes the binding of an amino acid to the trna

30
Q

Anticodon arm
Extra arm

A

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

31
Q

T¥C arm, loop IV

A

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

32
Q

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

A

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

33
Q

The 60S subunit is formed of

A

5S RNA
5.8S RNA
28S RNA
49 proteins

34
Q

40S subunit is formed of

A

18S RNA
33 proteins

35
Q

The svedberg unit depends on

A

Molecular weight
Particle size

36
Q

H1 histones can become
H2A may become

A

phosphorylated during condensation
linked to ubiquitin

37
Q

who is 140 bp?
who is 60 bp?

A

nucleosome
linker DNA

38
Q

telomeres contain

A

TTAGGG
variable repeat number

39
Q

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

A

yes

40
Q

30S subunit contains
50 S

A

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

41
Q

Non coding RNA

A

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

Molecular (6 decks)

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