6. Nucleic acids and protein synthesis

state two nucleic acids.

DNA and RNA

what is the name of the sub unit of nucleic acids? outline their structure.

nucleotides

phosphate group

nitrogenous base

pentose sugar (deoxyribose in DNA and ribose in RNA)

state the bases in DNA and state whether they have double helix or single strand?

adenine A

thymine T

cytosine C

guanine G

double helix

state the bases in RNA and state whether they are double helix or single strand?

adenine A

uracile U

cytosine C

guanine G

single strand

what is the name (full) of the molecule that carries energy?

adenosine triphosphate (ATP)

what type of molecules is ATP and what are it’s monomers?

nucleic acid , nucleotides

state the 2 structural forms of nucleotides and state their structural difference and what base are in them.

purines , double ring , adenine (A) guanine (G)

pyrimidines , single ring , thymine (T) cytosine (C) uracile (U)

DNA strands stays side by side and move in opposite direction. what is this called?

antiparallel

what bond links nucleotides in same strand toghether?

phosphodiester bond

how do we say that DNA moves in opposite direction.

one is 5’ to 3’ and one is 3’ to 5’

state the bonds between the nitrogen bases and state which base has how many bonds. What is the name of this type of bonding.

h bonds

adenine (A) and thymine (T) had 2 bonds

cytosine (C) and guanine (G) has 3 bonds

complementary base pairing

why DNA replication is semiconservative ?

half of the original molecule is conserved

outline the process of DNA replication.

helicase breaks the bonds between base pairs

double helix unwinds

each strand acts as a template

free nucleotides with 2 extra phosphates in nucleus align with their complementary bases on each of the strand

DNA polymerase systhesises new strand

DNA polymerase cleaves the two extra phosphates and uses the energy released to create phosphodiester bonds between adjacent nucleotides

hydrogen bonds forms between complementary base pairs between the new and original strands

explain why there a leading and lagging strand during DNA replication?

DNA polymerase can only build the new strand in one direction (5’ to 3’)

in the leading strand (5’ to 3’) DNA polymerase can systhesise the strand continuously

in the lagging strand (3’ to 5’) DNA polymerase needs to go back and forth making segments

segments are called okasaki fragments

DNA ligase join the okasaki fragments together to form continuous strand (by phosphodiester bonds)

state the examples of RNA molecules.

messenger RNA (mRNA) , transfer RNA (tRNA) , ribosomal RNA (rRNA)

The DNA nucleotide base code found within a gene is a ________ letter code.

3

the sequence of code which codes for an amino acid are called ___________.

codons

what is the start and stop codon.

TAC methionine

what does it mean for the code to be degenerate ?

multiple codons codes for the same amino acid

why do we say that the genetic code is universal ?

every organism uses the same code

what are the 2 stages of protein synthesis.

transcription and translation

outline the transcription stage of protein synthesis.

helicase unwinds the DNA strands by breaking h bonds

free activated RNA nucleotides pair up with their complementary bases on one strand of unzipped DNA

RNA polymerase forms the sugar phosphate backbone via phosphodiester bonds

mRNA is formed

the mRNA and DNA strands break and the double stranded DNA reforms

mRNA leaves the nucleus via nuclear pores

explain the translation stage of protein synthesis.

mRNA attaches to a ribosome

tRNA bind with their amino acids and bring them to the mRNA on the ribosome

anticodon on tRNA pairs with codon on mRNA

peptide bonds forms between adjacent amino acids

this continues until stop codon is reached

how is called the strand of DNA which is transcribed into mRNA ?

template strand

what are the names of the coding and non coding sequences ?

exons and introns

how is the removal of introns called?

post transcriptional modification

state the order of protein synthesis stages.

1. transcription

2. removal of introns

3. translation
   

what is a gene mutation?

a change in the sequence of base pairs which results in an altered polypeptide

what properties of the code allows that gene mutation often does not change the protein.

the code is degenerate , that is multiple codons codes for the same amino acid

state the different types of gene mutations .

insertion , deletion and substitution

explain insertion mutation. State another name for it.

a nucleotide is randomly inserted in the code , frameshift mutation

explain deletion mutation. State another name.

a nucleotide is randomly deleted from the code , frameshift mutation

explain substitution mutation.

a base in the sequence is randomly swapped with another base