DNA, genes and protein synthesis

Question 1

Gene

Answer 1

Unit of hereditary passed down from a parent to its offspring to determine characteristics

Question 2

Degenerate code

Answer 2

Different codons specify for same amino acid (e.g. val, gly, ala)

Question 3

STOP codons

Answer 3

End of a polypeptide chain
Do not code for anything

Question 4

Exons

Answer 4

Code for a protein

Question 5

Intron

Answer 5

Non-coding sequences, interrupts gene sequence

Question 6

How to interpret genetic code on a table

Answer 6

1st base: Column on left
2nd base: Row at top
3rd base: Column on right

Question 7

How DNA is paired into chromosomes

Answer 7

1) Helix wound around histones
2) It’s fixed in position
3) DNA-histone complex coiled
4) Packed into chromosome
5) DNA condensed into 1 chromosome
6) Forms single molecule of DNA

Question 8

What are homologous pairs

Answer 8

Literally the X chromosomes make
2 chromosomes in a pair ( I + I = X )
States that one is inherited from mother, and the other from father

Question 9

Diploid number

Answer 9

Number of chromosome pairs
E.g. - humans have 46

Question 10

Allele

Answer 10

Alternative forms of a gene

Question 11

What happens if you change a base sequence

Answer 11

Mutation
Different amino acid sequence leads to production of different polypeptide, different protein

Question 12

What does mRNA stand for

Answer 12

Messenger RNA

Question 13

What does messenger rna do

Answer 13

Transfers DNA from nucleus to cytoplasm
Contains coded information to determine the sequence of amino acids (i.e. carries instructions to make proteins)

Question 14

How does mRNA leave the nucleus and why

Answer 14

Leaves nucleus through nuclear pores
Enters cytoplasm and associates with ribosomes
For protein synthesis

Question 15

Genome

Answer 15

Complete set of genes in a cell

Question 16

Proteome

Answer 16

Range of proteins produced by genome

Question 17

What is rna for

Answer 17

Making proteins

Question 18

What is RNA made up of

Answer 18

Pentose sugar
Phosphate group
Adenine, guanine, cytosine, uracil

Question 19

What does mRNA do in the cytoplasm

Answer 19

Associates with ribosomes
And
Acts as a template for protein synthesis

Question 20

Why is mRNAs structure suited for its function

Answer 20

Contains information for production of amino acids IN THE FORM OF CODONS

Question 21

What does tRNA stand for

Answer 21

Transfer RNA

Question 22

Shape of tRNA

Answer 22

Clover leaf

Question 23

What is a feature of tRNA’s structure for protein synthesis

Answer 23

Top of clover leaf one end comes out more than the other
Amino acids can easily attacg

Question 24

How does the tRNA know how to bind to which amino acids

Answer 24

Each tRNA is specific to a certain amino acids because of its specific anticodon

Question 25

What’s an anticodon

Answer 25

Sequence of 3 bases at bottom of clover leaf

Question 26

What does it mean if the code is degenerate

Answer 26

Amino acid coded by more than one codon

Question 27

Complementary base pairs RNA

Answer 27

Guanine and cytosine Adenine and uracil

Question 28

How proteins are formed in DNA summary

Answer 28

1) DNA provides instructions in form of bases 2) Transcription 3) pre-mRNA spliced into mRNA 4) Translation

Question 29

Bakery analogy of protein synthesis

Answer 29

OVEN = cell organelles -> manufacture proteins CAKE = protein -> make many different types INGREDIENTS = amino acids -> make proteins TYPE OF CAKE RECIPE = genetic code -> can choose different genetic codes depending on what’s needed MANY COPIES OF RECIPE BOOK = genome -> contains all information needed for a person PHOTOCOPY RECIPE = transcription -> copy of DNA MAKING CAKES = translation -> making proteins using transcription (making cakes using photocopied recipe)

Question 30

What does transcription and translation do

Answer 30

Transcription = copying DNA Translation = making proteins

Question 31

Process of transcription

Answer 31

1) Nucleotide bases exposed by enzyme acting on DNA strand, splitting it into RNA 2) Template strand pairs with complementary nucleotides 3) RNA polymerase moves along strand joining nucleotides by peptide bond 4) DNA strand rejoins behind it 5) Enzyme reachers terminator sequences, detaches and pre-mRNA production is complete

Question 32

What does splicing in eukaryotic cells form

Answer 32

Splicing of pre-mRNA forms mRNA

Question 33

What is DNA made up of

Answer 33

Made up of exons that code for proteins and introns These introns prevent synthesis of a polypeptide

Question 34

What does splicing do

Answer 34

Removes base sequences corresponding to introns Functional exons are joined together

Question 35

Synthesising a polypeptide contains what

Answer 35

mRNA strand along the bottom Ribosome moves along mRNA strand tRNA (clover leaf, peg looking shapes) Amino acids attached ontop of tRNA Bases attached to tRNA and mRNA Peptide bonds

Question 36

Process of forming a polypeptide chain

Answer 36

1) Ribosome attaches at starting codon (first 3 bases on mRNA) 2) tRNA and mRNA’s complementary bases pair up (a and u, g and c) 3) Ribosome moves along, pairing next set of bases 4) 2 amino acids on tRNA join by peptide bond (using enzyme and ATP) 5) Once 3 sets of bases have paired up, first amino acid on tRNA is released forming chain of amino acids. tRNA is free to collect another amino acid (peg) 6) Continues until STOP codon 7) Amino acids form a chain off tRNA

Question 37

Assembling a protein after polypeptide formation

Answer 37

Polypeptide is coiled or folded into secondary structure Secondary structure is folded into tertiary structure Different polypeptide chains link to form quaternary structure

Question 38

Bond in DNA

Answer 38

Phosphodiester

Question 39

What is a phosphodiester and hydrogen bond between

Answer 39

Phosphodiester = nucleotides Hydrogen = bases

Question 40

Describe two differences between the structure of tRNA and mRNA

Answer 40

tRNA is a clover leaf shape, mRNA is linear tRNA has hydrogen bonds, mRNA does not tRNA has anticodon, mRNA has codon tRNA has amino acid binding site, mRNA does not

Question 41

Describe and explain difference in structure of mRNA and pre-mRNA

Answer 41

1) mRNA has fewer nucleotides Pre-mRNA more nucleotides OR mRNA has no introns Pre-mRNA has exons and introns 2) because of splicing

Question 42

Describe how one amino acid is added to a polypeptide that is being formed at a ribosome during translation

Answer 42

TRNA brings specific amino acid to ribosome Anticodon binds to codon Amino acids join by condensation reaction using ATP/amino acids join to form a peptide bond

Question 43

Describe how mRNA is produced from an exposed template strand of DNA. Do not include DNA helicase or splicing in your answer

Answer 43

Free RNA nucleotides from complementary base pairs Phosphodiester bond forms By RNA polymerase

Question 44

Describe how mRNA is formed by transcription in eukaryotes

Answer 44

1) Hydrogen bonds break between DNA bases 2) One DNA strand acts as a template 3) Free RNA nucleotides align by complementary base pairing 4) Uracil base, pairs with adenine on DNA 5) RNA polymerase joins nucleotides 6) Phosphodiester bonds form 7) Pre-mRNA is splices to form mRNA

Question 45

Describe how a polypeptide is formed by translation of mRNA

Answer 45

1) Ribosomes attach with mRNA 2) Anticodons bind to complementary codons 3) tRNA brings specific amino acid 4) Amino acids join by peptide bonds 5) Amino acids join using ATP 6) tRNA is released 7) The ribosome moves along the mRNA to form the polypeptide

Question 46

Describe how mRNA is produced in a plant cell

Answer 46

1) DNA strands separate breaking H bonds 2) One of template strand used to make mRNA 3) Complementary base pairing A and U, T and A, C and G, G and C 4) Nucleotides join by RNA polymerase 5) Pre-mRNA formed 6) Splicing to form mRNA

Question 47

Describe the role of a ribosome in the production of a polypeptide. DO not include transcription in your answer

Answer 47

1) mRNA binds to ribosome 2) Two codons 3) tRNA binds with anticodons 4) Catalyses formation of peptide bond between amino acids 5) Moves mRNA to next codon (translocation)