Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

jc1 biology > dna structure > Flashcards

dna structure Flashcards

(71 cards)

Start Studying
1
Q

what are polynucleotides

A

polymers of nucleotides

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

monomers of nucleic acids

A

nucleotides

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

what are the two types of nucleic acids

A

deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)

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

a nucleotide consists of what components?

A

a nitrogenous base, a pentose sugar (i.e. 5-carbon sugar), and a phosphoric acid / phosphate group

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

the components of nucleotides are ___ bonded together

A

covalently

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

what type of pentose does DNA and RNA contain respectively?

A

DNA: deoxyribose
RNA: ribose

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

how does deoxyribose and ribose differ from each other?

A

In ribose, the carbon at the C-2 position is attached to a hydroxyl (OH) group. In deoxyribose, the carbon at the C-2 does not contain this hydroxyl group; rather it is replaced by a hydrogen (H) atom.

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

is DNA or RNA more chemically reactive? why?

A

RNA is more chemically reactive as the -OH group of RNA is more polar than the -H in DNA.

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

what is the significance of DNA being less chemically reactive than RNA?

A

DNA is generally the primary molecule for storage of genetic info due to its chemical stability.

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

what are the five different nitrogenous bases?

A

adenine, guanine, cytosine, thymine (DNA only), uracil (RNA only)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
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
12
Q

which nitrogenous bases are pyrimidines?

A

cytosine, thymine (DNA only), uracil (RNA only)

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

how many carbon-nitrogen rings do purines and pyrimidines have respectively?

A

purines: two carbon-nitrogen rings
pyrimidines: one carbon-nitrogen ring

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

formula of phosphoric acid / phosphate group

A

H₃PO₄

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

what gives a nucleic acid its acidic character + negative charge?

A

it’s phosphate group

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

nucleotides can also be referred to as

A

nucleoside mono/di/triphosphate

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

what is a nucleoside

A

the pentose sugar + nitrogenous base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what are the two condensation reactions in the formation of a nucleotide?

A

base + sugar -> nucleoside + water
nucleoside + phosphoric acid -> nucleotide + water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what type of reaction forms a polynucleotide?

A

condensation reaction (that is repeated many times)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What type of bond connects two nucleotides?

A

A phosphodiester bond (a covalent phosphate-hydroxyl ester bond)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the function of a phosphodiester bond?

A

It gives strength and stability to the polynucleotide.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What pattern does the polynucleotide backbone follow?

A

An alternating pattern of sugar and phosphate units.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

is the sugar-phosphate backbone positively or negatively charged?

A

negatively

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is attached to the sugar-phosphate backbone?

A

Nitrogenous bases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
What determines the organism’s development in a polynucleotide sequence?
The sequence of nitrogenous bases.
25
What is found at the 5’ end of a polynucleotide chain?
A phosphate group attached to carbon 5 of a sugar residue.
26
What is found at the 3’ end of a polynucleotide chain?
A hydroxyl (-OH) group on carbon 3 of a sugar residue.
27
Where are new nucleotides added in a polynucleotide chain?
only to the 3’ end.
28
what direction does a polynucleotide have
5' to 3'
29
describe how a phosphodiester bond is formed
a condensation reaction occurs between the 3'OH group of the nucleotide at the 3' end of the chain, and the 5' phosphate group of an incoming nucleoside triphosphate. one water molecule and 2 Pi (inorganic phosphate) are removed.
30
one complete turn along the helix has ___ base-pairs and spans ___nm
10 base-pairs, 3.4nm
31
most naturally occurring DNA is a left/right-handed helix
right-handed
32
why is most naturally occurring DNA a right-handed helix
it has greater thermodynamic stability than left-handed helix
33
what stabilises the structure in DNA
the hydrophobic interactions between the stacked nitrogenous bases
34
are the two strands in DNA parallel or anti-parallel?
anti-parallel
35
what is meant by the two strands in DNA being anti-parallel?
the 5' end of one chain lies next to the 3' end of the other chain
36
Chargaff's rule / base-pairing rule
Adenine of one strand base pairs with thymine on the other strand. Guanine on one strand base pairs with cytosine on the other strand. As a result, the ratio of purines (A+G) to pyrimidines (C+T) in a double stranded DNA molecule is 1:1.
37
what holds the two strands of DNA together?
hydrogen bonds between the nitrogenous bases
38
how many hydrogen bonds are there between A and T, and G and C respectively?
A and T: 2 G and C: 3
39
what is the constant width of the double helix
2.0nm
40
what is the significance of complementary base pairing
[i think i have a better answer in my tutorial, rewrite when i get answers] Complementary base pairing enables the synthesis of a complementary strand using a template strand. This forms the basis of semi-conservative DNA replication, ensuring accuracy during nuclear division, as well as genetic stability during reproduction.
41
what's the difference between the terms DNA molecule, DNA strand, and DNA polynucleotide?
DNA molecule: typically refers to double-stranded DNA (most common), but can also refer to single stranded DNA (e.g. in viruses) DNA strand: refers to ONE of the two strands of a double stranded DNA molecule DNA polynucleotide: refers to a polymer of deoxyribonucleotides joined by phosphodiester bonds
42
function of DNA
DNA is the heritable genetic material found in all living things. It carries the genetic information needed for all cellular activities.
43
What type of replication does DNA undergo?
Semi-conservative replication.
44
What role do both DNA strands play during replication?
Both strands act as templates to which a complementary set of nucleotides will attach by complementary base pairing via hydrogen bonding
45
What are the products of DNA replication?
Two daughter DNA molecules, each with identical base sequences to the original DNA.
46
What does each daughter DNA molecule consist of?
One parental strand and one newly synthesized strand.
47
in the event of mutation of one DNA strand, how does the intact strand aid in repair?
the intact strand can be used as a template to guide the repair via complementary base pairing
48
what stabilises the structure of the double helix?
the hydrogen bonds between complementary bases, the phosphodiester bonds between adjacent nucleotides (which are strong covalent bonds), and the hydrophobic interactions between the stacked nitrogenous bases
49
the importance of complementary base pairing and hydrogen bonding is shown in which four areas?
in DNA replication, in DNA repair, stability of DNA molecule, transcription of DNA
50
does RNA normally occur as a single or double stranded molecule?
single-stranded
51
where is mRNA transcribed in eukaryotes
in the nucleus
52
3 types of RNA
1) messenger RNA (mRNA) 2) ribosomal RNA (rRNA) 3) transfer RNA (tRNA)
53
main function of mRNA
carries genetic information from nucleus to cytoplasm for polypeptide synthesis via translation on ribosomes
54
What causes the tRNA strand to fold into a cloverleaf-shaped structure?
Hydrogen bonding between complementary bases.
55
what is the 2d structure of tRNA?
A cloverleaf-shaped structure with 3 hairpin loops.
56
what is the 3d structure of tRNA?
A compact L-shaped structure.
57
where is the anticodon included in tRNA
the loop protruding from one end of the structure
58
what is the anticodon in tRNA
a sequence of 3 nucleotides that are complementary to the codons on mRNA
59
What are aminoacyl-tRNA synthetases?
Enzymes that attach amino acids to tRNA molecules.
60
What is the main function of tRNA?
To carry a specific amino acid to a specific codon on the mRNA for polypeptide synthesis on ribosomes.
61
which RNA is the most abundant RNA? what percentage of this RNA comprises the total RNA in cells?
rRNA, ~80%
62
where are rRNA genes located in eukaryotes?
in the nucleolus
63
structure of rRNA
3D globular conformation
64
what causes the 3D globular conformation of rRNA
hydrogen bonding between complementary bases along the single RNA strand
65
main function of rRNA
major component of ribosomes
66
what enzyme does part of rRNA form
peptidyl transferase
67
function of peptidyl transferase
catalyses the formation of peptide bonds between amino acids during translation
68
rRNA helps to ___ mRNA in the ribosome
align
69
why does rRNA help align mRNA in the ribosome?
so that anticodons of incoming aminoacyl-tRNA molecules can complementary base pair / form hydrogen bonds with mRNA codons.
70
rRNA ___ the aminoacyl-tRNA ___
rRNA orientates the aminoacyl-tRNA in the correct position within the ribosomes binding sites (A, P, E sites)

jc1 biology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions