Chromosomes & DNA

Question 1

• What is a chromosome?
• What is chromatin?
• A chromosome consists of what?
• What is a chromatid?
• Where are chromatids attached? aka
• What is the function of the centromere?

Answer 1

• A tightly packed DNA structure visible during cell division.
• Uncoiled, thread-like DNA present during interphase.
• Two chromatids.
• One DNA molecule with proteins.
• At the centromere.
• Holds chromatids together and forms arms.

Question 2

• What are chromosome arms?
• What are telomeres?
• What is secondary constriction?
• What is nucleolar organizer?
• What is a satellite in a chromosome?
• What is junk DNA?

Answer 2

• Regions from centromere to ends.
• Protective ends of chromosomes preventing sticking.
• Extra narrow region along the chromosome.
• Region that helps form nucleolus.
• Knob-like structure after secondary constriction.
• Non-coding DNA with no clear function.

Question 3

• Metacentric chromosome?
• Submetacentric chromosome?
• Acrocentric chromosome?
• Telocentric chromosome?
• Chromosome composition?
• DNA is negatively charged because?
• Why does DNA bind histones?
• Histones contain which amino acids?
• DNA length in a human chromosome?
• What happens in S phase?
• After replication, what happens?
• When do chromosomes become visible?

Answer 3

• Centromere in the center → equal arms.
• Centromere slightly off-center → unequal arms.
• Centromere near end → one very short arm.
• Centromere at end → only one arm.
• 40% DNA + 60% protein.
• Because of phosphate groups.
• Histones are positively charged and DNA is negative.
• Arginine and lysine.
• About 5 cm (very tightly packed).
• DNA replicates.
• DNA and histones reorganize and condense.
• During cell division.

Question 4

organization of chromosome occurs in?
nucleosome string?
size?

Question 5

supercoil?
chromatids?

Question 6

chromatin fibre? thick size?
when is it found?
shows how many regions?

Answer 6

its a level of organization of chromosomes

Question 7

griffith’s experiement?

Question 8

hershey & chase experiments? claim?

Question 9

DNA replication? it happens in what phase? end product?
parent DNA? daughter DNA?

Question 10

semi-conservative model?

Question 11

conservative model?

Question 12

dispersive model?

Question 13

diagram of DNA replication?

Question 14

meselon & stahl experiment?
what was their aim?
steps?
conclusion?

Question 15

initiation phase?
define origin of replication?
how many in prokary & eukary?
how is replication bubble formed?
what enzymes are used? function of each?
what prevents the base pairs to pair up again cz they have attraction b/w them?
replication fork?

DNA replication

Answer 15

SSB proteins

replication fork is Y shaped

Question 16

extension phase? aka?
daughter strands synthesized by enzyme?
this enzyme cannot work unless? what is done for this?
define primosome

DNA replication

Question 17

different forms of DNA polymerase enzyme?

Answer 17

3

Question 18

mechanism of DNA polymerase-III activity?
why is the direction for ______ 3’ to 5’ or 5’ to 3’?
function of DNA polymerase-III?
leading strand? direction towards?
lagging strand? direction towards? why is it called it?
what are the fragments called?
what is proofreading?

Answer 18

adding a nucleotide to primer
5’ to 3’

Question 19

termination phase?

DNA replication

Question 20

DNA stability & variability?
how do mutation happen?

Question 21

gene expression aka? involves what processes?
first step of gene experession? occurs in? what does it require? is it a continuous process? phases?

Question 22

initiation phase? begins with?
what is promoter region?
what are the binding sites called in prokaryotes and eukaryotes?
what do the numbers mean?

gene expression

Question 23

• RNA polymerase consists of?
• haloenzyme?
• how does RNA polymerase gets attached to the promoter?
• how is RNA polymerase similar/different to DNA polymerase?
• types of RNA polymerase in pro & eu? function of each
• what happens after RNA polymerase binds to the promoter region?

Question 24

elongation phase?
does it require primer?
what are the 2 strands of the DNA called? aka?
RNA polymerase moves from? towards?
this phase continues until?

gene expression

Answer 24

(transcription)

Question 25

termination phase? what stops the synthesis of mRNA? what does terminator region consist of? GC hair pin? causes what? | gene expression

Answer 25

| (transcription)

Question 26

post transcriptional modification of mRNA? in prokaryotes? prokaryotes & eukaryotes? why do they need modification? what are introns? involves how many events?

Answer 26

2

Question 27

cap is in the form of? linked from? what abt the tail? consist of? name? these modif. prevents? RNA spicling? enzymes? exon fragments are joined by?

Question 28

gene? function? order of amino acids in a polypeptide is according to? define genetic code? 2 definitions? mRNA transcript consists of? how do 4 letters specify 20 amino acids?

Question 29

codon? total codons? stop/sense codons? name it? present on? non sense codons? what is start codon? function?

Question 30

genetic code characteristics? code degeneracy? is genetic code universal? how is it?

Answer 30

4

Question 31

translation? phases?

Question 32

activation of amino acids? means? complex name? enzyme?

Question 33

formation of initiation complex? process of translation actually begins with? what does it contain? explain the process what happens first?

Question 34

P site? A site? E site? | translation

Answer 34

pg 363

Question 35

polypeptide elongation? steps? define translocation?

Question 36

termination? | translation

Question 37

fate of synthesized protein? what happens after termination? it can be used as what? a cell can secrete protein in the form of?

Question 38

diff between translation in prokaryotes & eukaryote?

Question 39

gene expression? what is regulation of gene expression? mature human body is composed of how many cell types? the differences between cell types are there because?

Question 40

importance of regulation of gene expression? what if gene regulation is distrubed?

Question 41

methods of regulation of gene expression? 2 ways?

Question 42

lac operon? examples?

Question 43

mutation? size? mutagens? mutant?

Question 44

sources of mutagens?

Question 45

mutagenesis? types of mutation? based on?

Question 46

types of mutation on the basis of where and to what extent it occur?

Question 47

harmful aspects of mutation?

Answer 47

* A mutation that decreases the fitness of the organism in the environment is called harmful mutation. * There are many such examples like * (a) born without a part of the brain * (b) cancer is a form of a harmful mutation * (c) the developmental abnormalities, such as microcephaly, cleft palate, cases of abnormal number of chromosome (Down syndrome, Klinefelter’s syndrome, Turner’s syndrome etc.) * and heredity disorders like sickle cell anaemia, phenylketonuria etc.

Question 48

* useful aspects of mutation? * Q: What effect do changes in developmental genes have? * Q: What do scientists suspect about changes in developmental genes? * Q: Give three examples of large-scale evolutionary transformations possibly explained by developmental changes.

Answer 48

* A: Changes in the genes controlling development can have major effects on the morphology of the adult organism. * A: Scientists suspect that changes in developmental genes have helped bring about large-scale evolutionary transformations. * A: How some hoofed mammals evolved into ocean-dwellers, how water plants invaded the land, and how small, armoured invertebrates evolved wings.

Question 49

define chromosomal mutation? aka name some

Answer 49

3

Question 50

down syndrome? symtoms? caused by? treatment?

Answer 50

* Symptoms include * abnormal shaped smaller sized head, * rounded inner corner of the eyes instead of pointed, excess skin at the back of neck; * flattened nose; * single crease in the palm of the hand; * small ears; * small mouth; * wide, short hands with short fingers; * white spots on the coloured part of the eye, * excessive space b/w large toe & second toe.

Question 51

klinefelter syndrome?symtoms? caused by? show trisomy in? treatment? diagram?

Question 52

turner syndrome? 2n? symtoms? caused by? treatment?

Question 53

point mutation? aka?

Question 54

sickle cell anemia? symtoms? caused by? treatment?

Question 55

PKU? symtoms? caused by? treatment?

Question 56

inheritance pattern of sca & PKU?