DNA Prop. Lec 1

Question 1

Secondary

Answer 1

Interaction between the two DNA strands. Two strands held by H-Bonds, not as stable

Question 1

Primary Structure

Answer 1

sequence of nucleotides in single DNA strand. They are bonded together by phosphate groups. Stronger covalent bonds hold together. Presrves structure for genes.

Question 2

Tertiary

Answer 2

3-D structure (helix) of dsDNA

Question 3

Quaternary

Answer 3

Interactions with other molecules

Question 4

Nucleotide

Answer 4

1) Deoxiribose sugar
2) Phosphate group
3) CAGT

Question 5

Purines

Answer 5

Double Rings (AG)

Question 6

Pyrimidine

Answer 6

Single Ring (CT)

Question 7

Base Pairing

Answer 7

Partial charges between base pairiing is symmetrical
A-T 2H bonds
c-G 3H bonds

Question 8

Antiparallel

Answer 8

Reverse compliment, reverse reading direction

Question 9

DNA Forms

Answer 9

B DNA
A DNA
Z DNA

Question 10

Helix shape

Answer 10

bases are hyrdophobic
backbone is not, negative charge

Question 11

B DNA

Answer 11

Most common
clockwise spiral
major and minor grooves (protein interaction)

Question 12

A DNA

Answer 12

Pretty rare
Shorter and wider than B
Right-handed helix
Grooves less accessible
Dehydrated

Question 13

Z DNA

Answer 13

Slightly less common
Left Handed
no major groove
transcrip. inactive

Question 14

+ vs - DNA constriction/relaxion

Answer 14

+ is when DNA twists the same way
- is DNA opposite way (relaxes)

Question 15

supercoiling

Answer 15

Double helix winds around itself and shortens

Question 16

+ Supercoiling

Answer 16

Rotated in clockwise direction.
- Constricts/strains DNA.
- Mediated by topoisomerases.

Question 17

• Supercoiling

Answer 17

Counter-rotations in opposite direction of double helix twist.
- Relaxes DNA, exposes bases.
- Can unwind spontaneously

Question 18

Centromere

Answer 18

Tightly-packed non-coding DNA near
the “center” of chromosomes.
necessary for cell division in eukaryotes

Question 19

Telomeres

Answer 19

1000s of short non-coding DNA repeats
at chromosome ends.
Without telomeres to degrade, lost DNA
might be part of functional genes.

Question 20

Chromatin

Answer 20

Histone proteins condense eukaryotic chromosomes, creating a DNA-protein
complex: chromatin

Question 21

Euchromatin

Answer 21

loosely packed active DNA

Question 22

Heterochromatin

Answer 22

tightly packed inactive DNA

Question 23

n-number (n=23 vs 2n=46 etc.)

Answer 23

haploid number
or number of chromosomes in normal gametes

Question 24

G1

Answer 24

• Cell growth.
• Organelles created.
• Cell readies for replication by synthesizing replication enzymes

Question 25

G1/S checkpoint

Answer 25

hold until replication
enzymes and growth factors reach critical concentration

Question 26

S

Answer 26

DNA Rep
sister chromatids formed

Question 27

Homologs

Answer 27

• One paternal, one maternal.
• Same genes but non-identical.
• During S phase, each homolog is replicated

Question 28

G2

Answer 28

Centrosomes and kinetochores
form.

Question 29

G2/M checkpoint

Answer 29

DNA repair fixes enzymes
If fail triggers cell death

Question 30

Prophase

Answer 30

chromatin condense
spindle begins to form
sister chromatids are bound by cohesin

Question 31

Prometaphase

Answer 31

Nuclear envelope disintegrates

Question 32

Metaphase

Answer 32

Microtubules line chrom on metaphase plate
spindle-assembly checkpoint

Question 33

Anaphase

Answer 33

Cohesin binding the sister chromatids degrades
pulled apart

Question 34

Telophase

Answer 34

nuclear membranes reform in daughter cells
spindle degrades

Question 35

cytokinesis

Answer 35

Cleavage furrow pinch

Question 36

Meiosis 1 vs Meiosis 2

Answer 36

1) reductional division
2) same as mitosis

Question 37

Crossing Over

Answer 37

Prophase 1
broken ends exhange places
these sites are called chiasmata

Question 38

Shugoshin and Cohesin

Answer 38

Shugoshin protects the cohesin holding the centromeres together so that only the homologous chromosomes separate in ana 1. In Ana 2 shugoshin is degraded so that sister chromatids separate.