Nucleic Acids Flashcards Preview

Biology A Level > Nucleic Acids > Flashcards

Flashcards in Nucleic Acids Deck (22):
1

What is a nucleotide?

molecule consisting of a 5-carbon sugar, phosphate group, nitrogenous base
are phosphate esters of pentose sugars

2

Nucleotides form the ________ of _______ _____

monomers
nucleic acids (DNA, RNA)

3

the nucleotide pentose sugar of DNA is...

deoxyribose

4

the nucleotide pentose sugar of RNA is...

ribose

5

if nucleotides contain more than 1 _________ group, they become ______________ ___________

phosphate
phosphorylated nucleotides (ADP, ATP)

6

nucleotides can...
and can be...

regulate metabolic pathways
components of coenzymes

7

What is the bond between a 5-carbon sugar and a phosphate group?

phosphodiester

8

A
C
G
T

Adenine
Cytosine
Guanine
Thymine

9

2 ______________ strands of DNA run ____ ________ and are joined by ________ _____.

polynucleotide
anti parallel
hydrogen bonds

10

adenine and guanine are...
thymine and cytosine are...

purine nitrogenous bases (2 rings)
pyrimidine (1 ring)

11

A-T have...
G-C have...

2 hydrogen bonds
3 hydrogen bonds

12

the upright part of a large DNA molecule is...

the sugar-phosphate backbones of anti parallel polynucleotide strands

13

5' is when...
3' is when...

the phosphate group is attached to the 5th carbon of deoxyribose sugar
phosphate group is attached to the 3rd carbon

14

Semi-conservative replication is...

2 new molecules, each has one old and one new strand. The old strand is conserved.

15

DNA replication process:

1) DNA molecule unwinds and double helix untwists (gyrase enzyme)
2) unzips hydrogen bonds between nucleotide bases, so 2 single strands now (DNA helicase)
3) free phosphorylated nucleotides in nucleoplasm in nucleus bond to exposed bases. In 5' to 3', leading strand synthesised continuously, lagging strand in fragments (DNA polymerase). Lagging strand later joined (ligase enzyme)
4) phosphodiester bonds between sugar residue of 1 nucleotide and phosphate group of the next. The energy comes from, hydrolysis of activated nucleotides to release extra phosphate groups
5) 2 DNA molecules

16

Mutation is when...

an error occurs and the wrong nucleotide is inserted which changed the genetic code.

17

Transcription

1) gene unwinds
2) H bonds between bases break
3) temporary H bonds between RNA nucleotides and unpaired DNA bases (template strand - DNA strand) (RNA polymerase)
4) length of RNA complementary to template strand produced - coding strand
5) mRNA out nucleus to ribosomes
6) DNA zips back up

18

RNA is different from DNA because...

it is single stranded and a shorter chain
there are 3 forms of RNA, messenger, transfer, ribosomal

19

Why is mRNA made?

instructions inside genes can't pass out the nucleus so it is copied/transcribed into mRNA.

20

Codons

sequence of base triplets

21

tRNA has an...

anti-codon on one end and an amino acid on the other
the anti-codon is complementary to the codon on mRNA

22

Translation

1) tRNA binds to mRNA triplet by temporary H bonds
2) ribosomes move along mRNA, reads code and amino acids join up by peptide bonds
3)mRNA breaks down, recycled and the polypeptide folds into 3D structure to carry out function.