Theme 1B

Question 1

what are the 3 things that DNA consists of

Answer 1

Penrose Sugar (Ribose and Deoxyribose), Nitrogenous bases, and Phosphates

Question 2

what are the purine bases

Answer 2

Adenine and Guanine, they have a double ring

Question 3

what are the pyrimidine bases

Answer 3

Cytosine, Thymine, and Uracil, they have a single ring

Question 4

what are nucleosides

Answer 4

molecules of a sugar and a base. sugars bind to N9 of purines and N1 of pyrimidines

Question 5

what is the difference between ribose and deoxyribose

Answer 5

riboses have and extra OH

Question 6

what are nucleotides

Answer 6

nucleosides and phosphates

Question 7

where is the phosphate group attached to the nucleoside

Answer 7

the carbon 5

Question 8

nucleotide monomers polymerize via ______

Answer 8

phosphodiester bonds

Question 9

covalent bonds form between phosphate and the

Answer 9

C-3’ and C-5’ of two pentose sugars (the pentose-phosphate backbone)

Question 10

polynucleotide has polarity with a ________

Answer 10

C-5’ PO4 end and a C-3’ OH end

Question 11

what is Chargaff’s Rule

Answer 11

%A = %T and %C = %G

Question 12

how are the % of purines and pyrimidines related

Answer 12

%Purines (A+G) = %Pyrimidines (C+T)

Question 13

who first showed the helical structure of DNA

Answer 13

Rosalind Franklin

Question 14

what is the diameter of DNA helix

Answer 14

2 nm

Question 15

is the DNA backbone hydrophilic or hydrophobic

Answer 15

hydrophilic

Question 16

are the DNA bases (the interior) hydrphilic or hydrophobic

Answer 16

hydrophobic

Question 17

how many hydrogen bonds do A and T have

Answer 17

2

Question 18

how many hydrogen bonds does G and C have

Answer 18

3

Question 19

which pair takes more energy to reannel after being denatured

Answer 19

GC

Question 20

what is chromatin

Answer 20

condensed DNA

Question 21

how is chromatin formed

Answer 21

DNA wrapped twiceish around histones to form a nucleosome. chromatin is formed by repeated nucleosomes that are connected

Question 22

how is 30 nm chromatin different from 10 nm chromatin

Answer 22

30 nm have more histones that cause it to coil more than 10 nm

Question 23

what is the ‘normal’ state of DNA molecules

Answer 23

chromatin

Question 24

are histones positively or negatively charged

Answer 24

positively

Question 25

what is a histone octamer

Answer 25

a nucleosome with ~147 by of DNA wrapped around it

Question 26

what is linker DNA

Answer 26

the DNA strands that connect the nucleosomes

Question 27

how does 30 nm chromatin form

Answer 27

histone H1 binds to nucleosomes and linker DNA to coil it further

Question 28

what is euchromatin

Answer 28

regions that have lower DNA compaction, where genes are actively expressed

Question 29

what is heterochromatin

Answer 29

chromosomal regions of high DNA compaction where gene expression is silenced

Question 30

what is constitutive heterochromatin

Answer 30

where DNA is always compacted (centromeres and sub-telomeric regions)

Question 31

what is facultative heterochromatin

Answer 31

heterochromatin that can switch to euchromatin depending on cell type and development

Question 32

what are 3 reasons for DNA organized as chromosomes

Answer 32

1. so it can fit into the cell/nucleus 2. it protects DNA from damage 3. easily separated and transmitted to each daughter cell during division

Question 33

what are origins of replication

Answer 33

multiple DNA sequences along chromosomes which initiate DNA replication

Question 34

what is a centromere

Answer 34

a sequence required for for correct segregation of chromosomes by directing formation of the kinetochore in which the mitotic spindle attaches

Question 35

what are telomeres

Answer 35

sequences located at the ends of the chromosomes that prevent degradation and allow proper replication

Question 36

what is ploidy

Answer 36

the number of chromosome sets

Question 37

what is the ploidy of most eukaryotic cells

Answer 37

diploid

Question 38

when do haploid cells occur in humans

Answer 38

during meiosis (gamete formation)

Question 39

into what shape is prokaryotic DNA organized

Answer 39

circle

Question 40

what are plasmids

Answer 40

small, circular DNA molecules that prokaryotes have, they can have multiple different plasmids, and multiple coppies of each plasmid

Question 41

are plasmids essential for life

Answer 41

no, they only have genes that may give them an advantage in some way