Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL243 > 1B: structure of DNA and genomes > Flashcards

1B: structure of DNA and genomes Flashcards

1
Q

what 3 components does DNA consist of?

A

equal parts:

1) pentose sugar
2) nitrogenous base
3) phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the two pentose sugars?

A

ribose (in RNA)

deoxyribose (in DNA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the general structure of pentose sugars? how do the two pentose sugars differ?

A

general: ring of 4 carbon atoms and 1 oxygen. one carbon atom branch on C4’ (beside the oxygen).
ribose: an OH and H bound to C2’
deoxyribose: 2 H bound to C2’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the 5 nitrogenous bases?

A

adenine, guanine, cytosine, thymine, uracil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

which nitrogenous bases are purines?

A

adenine and guanine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

which nitrogenous bases are pyrimidines?

A

cytosine, thymine, and uracil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the structural difference between purines and pyrimidines? where do pentose sugars connect to them?

A

purine: double ring, sugar binds to N9
pyrimidine: single ring, sugar binds to N1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the difference between adenine and guanine?

A

adenine: has NH2 group
guanine: has O where adenine has NH2 and NH2 group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the difference between cytosine, thymine, uracil

A

cytosine: has a NH2 group
thymine: has a H3C group
uracil: no additional groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is a nucleoside?

A

a pentose sugar bonded to a nitrogenous base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

which carbon on pentose connects to the base?

A

C1’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is a nucleotide?

A

a nucleoside plus triphosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are phosphodiester bonds?

A

the covalent bonds between nucleotide monomers (the DNA/pentose-phosphate backbone). the C5’ of one sugar connects to an O of the phosphate, and another O of the phosphate connects to C3’ of another sugar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are the two ends of a DNA strand?

A

5’ end: one w/ phosphate group bound to C5’ of a pentose sugar
3’ end: one w/ an OH group bound to the C3’ of a pentose sugar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the overall charge of DNA? what contributes to this?

A

overall negative–phosphate groups contribute to this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what did Erwin Chargaff discover about DNA’s structure?

A 
Chargaff's Rule: %A = %T; %C = %G
additionally:
➞%purines = %pyrimidines
➞C + G ≠ A + T
➞A C G and T are not present in equal amounts
17
Q

what could we tell from Rosalind Franklin’s x-ray diffraction studies of DNA?

A

➞DNA molecules are cylindrical with a ~2 nm diameter
➞0.34 nm periodicity suggests bases are stacked like pennies
➞x-shape pattern indicates helical structure.

18
Q

what 4 things did Watson and Crick discover about the structure of DNA?

A

➞two strands of the phosphate-pentose backbone spiral as a double helix about a common axis
➞the two strands are antiparallel (one strand is in the 5’-3’ direction, other is in 3’-5’)
➞a purine on one strand is always base-paired with a pyrimidine
➞the backbone/exterior is hydrophilic, the bases/interior are hydrophobic

19
Q

what keeps the two strands of DNA together?

A

hydrogen bonding between base pairs

20
Q

what is nucleic acid hybridization?

A

annealing of single strands of DNA or RNA by forming H bonds. the two strands must be complementary in sequence.

21
Q

where are DNA-RNA hybrids found?

A

DNA replication, transcription, and reproduction of some RNA viruses.

22
Q

what is semiconservative replication?

A

replication where the double helix of the new DNA contains one strand of the original/parent DNA and one new daughter strand.

23
Q

what structure is DNA stored in in organisms?

A

in chromosomes

24
Q

what is chromatin?

A

given region of DNA with its associated proteins on a chromosome

25
Q

how is DNA stored in prokaryotes?

A

in one (usually circular) chromosome, and plasmids in the cytoplasm

26
Q

what are plasmids?

A

small independent circular DNA in prokaryotes, that the cell could technically survive without

27
Q

how is DNA stored in eukaryotes?

A

in linear chromosomes enclosed within the nucleus

28
Q

what is chromosomal ploidy?

A

the number of copies of its chromosomes that an organism has

29
Q

how does one communicate that an organism has one set of each chromosome, two sets, or more than two?

A

➞haploid
➞diploid
➞polyploid

30
Q

what is the only cell type that has a haploid genome?

A

sperm and egg cells

31
Q

what is the purpose of being polyploid?

A

it increases protein production

32
Q

what are 3 reasons DNA is organized into chromosomes?

A

1) chromosomes compact DNA so it can fit in cells
2) chromosomal structure protects DNA from damage
3) chromosomes can be easily separated and transmitted to daughter cells in cell division

33
Q

what are histones?

A

basic, positively-charged proteins that DNA winds around

34
Q

what is a nucleosome?

A

a histone octamer

35
Q

what does histone H1 do?

A

binds linker DNA and binds to nucleosomes to form the 30nm chromatin fibre

36
Q

do all organisms have histones?

A

no–prokaryotes do not, but they have some other equivalent that does that same thing

BIOL243 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions