nucleotides and nucleic acids

Question 1

what is the monomer of DNA?

Answer 1

nucleotides

Question 2

what is the name of the polymer formed?

Answer 2

polynucleotide

Question 3

what is the name of the bond formed? And where is it formed?

Answer 3

phosphodiester formed between the phosphate of one nucleotide and the deoxyribose sugar of the next nucleotide

Question 4

what holds the bases together?

Answer 4

hydrogen bonds

Question 5

give the name of the 4 bases and what pairs with what

Answer 5

cytosine, adenine, guanine and thymine, A-T and G-C

Question 6

what is a purine structure?

Answer 6

double ring structure

Question 7

what is a pyrimidine structure?

Answer 7

single ring structured

Question 8

what are each of the bases

Answer 8

A&G are purine and C&T are pyrimidine

Question 9

how many hydrogen bonds are between C&G and A&T

Answer 9

C&G= 3, A&T=2

Question 10

what sugar does RNA contain?

Answer 10

ribose

Question 11

what replaces thymine in an RNA nucleotide and is it purine or pyrimidine?

Answer 11

Uracil (U) replaces thymine and it is pyrimidine

Question 12

what produces ATP ?

Answer 12

respiration

Question 13

how is the energy released for use in respiration?

Answer 13

constantly recycled

Question 14

what is ATP made from?

Answer 14

ADP and Pi, made from the terminal phosphate group of ATP releases usable energy for the cell

Question 15

what else are ATP and ADP known as?

Answer 15

phosphorylated nucleotides

Question 16

what do the polynucleotide strands twist and form?

Answer 16

double helix

Question 17

what is meant by anti-parallel and how does this relate to DNA?

Answer 17

polynucleotide strand is different at each end 3’ and 5’prime, the different strands run in opposite directions (anti-parallel) at each end of the strand is either 5’ or 3’

Question 18

how many bases code for an amino acid?

Answer 18

3 bases in sequence- the 4 bases can be arranged in 64 different ways to make groups of 3

Question 19

what is the group of bases called?

Answer 19

codon

Question 20

why is it referred to as a degenerate code?

Answer 20

some AA have more than 1 corresponding triplet- the 3rd code is usually said to be different so the code is siad to be degenerate

Question 21

where does transcription occur?

Answer 21

nucleus

Question 22

describe mRNA

Answer 22

ribose sugar, uracil base not thymine, mRNA is shorter than DNA and is a single strand mRNA carries a message from the DNA in the nucleus to the site of protein synthesis in the cytoplasm

Question 23

give a brief description of how transcription happens

Answer 23

helix unwinds and unzips, free RNA nucleotides complementary base pair, RNA nucleotides are joined by phosphodiester bonds joined by RNA polymerise, mRNA peels off the DNA and leaves the nucleus through the nuclear pore, DNA zips and twists back up together

Question 24

describe rRNA

Answer 24

eukaryotic ribosomes are and of one small and large sub-unit, sub-units made of ribosomal RNA

Question 25

what is the function of rRNA?

Answer 25

rRNA is important for maintaining structural stability during protein synthesis

Question 26

what is the function of mRNA?

Answer 26

codes for the correct sequence of AA

Question 27

what is the function of tRNA?

Answer 27

carries specific AA to the mRNA to be built into a chain

Question 28

describe the structure of tRNA

Answer 28

single strand of RNA folded into a cloverleaf or hairpin shape held together by complementary base pair

Question 29

Briefly describe transcription

Answer 29

mRNA enters the cytoplasm and attaches to a ribosome and the ribosome moves along until it reaches a codon, tRNA brings the correct AA for the codon and attaches when the anticodon binds to the codon, the next RNA arrives with a new AA, once aligned AA join with a peptide bond using peptidyl transferase and the ribosome moves along to the next codon, the old tRNA leaves to pick up a new AA and a new tRNA etc.

Question 30

What happens if replication makes a mistake?

Answer 30

May have no effect at more than one triplet codes for each AA or it may change the tertiary shape of the protein

Question 31

What does semi conservative mean?

Answer 31

Each original strand is used as a template for a new strand

Question 32

How does DNA replication happen?

Answer 32

Hydrogen bonds se broken, free nucleotides line up to the exposed bases, complementary base pairing, produce two double helices that are identical to the original one

Question 33

What does helicase do?

Answer 33

Breaks the hydrogen bonds between DNA

Question 34

What does DNA polymerase do?

Answer 34

Forms phosphodiester bond, joins together the nucleotides on new strands forming phosphodiester bonds

Question 35

Explain evidence for semi conservative replication

Answer 35

Experiments provide evidence that replication is semi conservative, bacteria grown on 15N, bacteria extracted and then grown on 14N, any new DNA would now be 14N, if grown on 14N it is less dense so settles higher up

Question 36

Where is DNA 15N

Answer 36

In the bases

Question 37

Why is semi conservative replication important

?

Answer 37

It conserves the genetic material accurately as exact copies are made

Question 38

What can sometimes happen?

Answer 38

Random spontaneous mutations may occur this is when the sequence of bases is not always matched exactly