dear god help us

What does DNA store and transmit?

Genetic information

What is the shape of the DNA molecule?

Helical double-stranded molecule

Which proteins bind DNA in eukaryotes?

Histones

What shape are eukaryotic chromosomes?

Linear

Where is DNA found in eukaryotic cells?

Nucleus

What shape is prokaryotic DNA?

Circular

Is prokaryotic DNA bound to histones?

No (unbound)

Where is DNA found in prokaryotes?

Cytosol

Which eukaryotic organelles contain circular DNA?

Mitochondria and chloroplasts

What is the monomer of DNA?

Nucleotide

What three parts form a DNA nucleotide?

Phosphate and sugar and base

Which sugar is found in DNA?

Deoxyribose

Which four bases are found in DNA?

Adenine thymine cytosine guanine

Which base pairs with adenine?

Thymine

Which base pairs with cytosine?

Guanine

How many hydrogen bonds join A and T?

Two

How many hydrogen bonds join C and G?

Three

Why are the bonds between DNA strands weak?

Allows strands to separate

Why is complementary base pairing important?

Ensures accurate replication

In which direction do humans read DNA?

5' to 3'

Which bond joins nucleotides within a strand?

Phosphodiester bond

What is DNA replication?

Copying DNA before division

Why is DNA replication semi-conservative?

One old one new strand

In replication what unwinds the double helix?

Helicase

Which bonds does helicase break?

Hydrogen bonds between strands

What does each parent strand act as?

Template

Which enzyme adds free nucleotides in replication?

DNA polymerase

In which direction is new DNA synthesised?

5' to 3'

To which end does polymerase add nucleotides?

3' end

What does DNA replication produce?

Two identical DNA molecules

Why must DNA double before cell division?

Daughter cells need full DNA

Which scientists helped develop the DNA model?

Watson, Crick, Franklin, Wilkins

What is a gene?

A gene is a specific sequence of DNA nucleotides that acts as a blueprint to create a functional product, usually a protein.

What can a gene code for?

Functional protein or RNA

What are exons?

Coding segments of genes

What are introns?

Non-coding segments of genes

Which gene segments are transcribed in eukaryotes?

Exons and introns

Which gene segments are translated?

Exons only

Do most prokaryotes have introns?

No

What are the end products of genes?

Protein tRNA rRNA microRNA

What are the two stages of protein synthesis?

Transcription then translation

What is transcription?

DNA copied into mRNA

Where does transcription occur in eukaryotes?

Nucleus

What happens to pre-mRNA before translation?

Introns spliced out

What is translation?

mRNA decoded into polypeptide

Where does translation occur?

Ribosomes

What is the role of mRNA?

Carries gene copy to ribosome

What is the role of tRNA?

Delivers amino acids

What is the role of rRNA?

Forms ribosome structure

What is a codon?

Three bases coding amino acid

What is an anticodon?

tRNA triplet complementary to codon

What is the template strand?

Strand transcribed into mRNA

What is the coding strand?

Matches mRNA sequence

Which base replaces thymine in RNA?

Uracil

What is the start codon?

AUG

What are the stop codons?

UAA and UAG and UGA

Which bond joins amino acids?

Peptide bond

What determines how a polypeptide folds?

Amino acid sequence

What is primary protein structure?

Amino acid sequence

Which bond stabilises primary structure?

Peptide bonds

What is secondary protein structure?

Alpha helices and beta sheets

Which bond stabilises secondary structure?

Hydrogen bonds

What is tertiary protein structure?

Three-dimensional polypeptide folding

Which bonds stabilise tertiary structure?

Hydrophobic interactions, disulfide bridges, hydrogen bonds, ionic bonds, van der Waals forces

What is quaternary protein structure?

Multiple polypeptides joined

Which proteins have quaternary structure?

Haemoglobin and DNA polymerase

Why is protein shape critical?

Determines protein function

Which proteins have specific shapes?

Enzymes, hormones, receptors, antibodies

What are ribozymes?

Catalytic RNA molecules

How do enzymes affect activation energy?

Lower it

Why are enzymes substrate specific?

Complementary active site shape

What is the induced-fit model?

Active site moulds around substrate

Which factors affect enzyme activity?

Temperature and pH and inhibitors

Which concentrations affect enzyme reaction rate?

Substrate and enzyme

What does high temperature do to enzymes?

Denatures them

What is denaturation?

Loss of three-dimensional shape

Which are examples of enzyme inhibitors?

Glyphosate and ritonavir

What do antibodies recognise?

Specific antigens

What is the ELISA assay?

Antibody-based diagnostic test

What controls cellular differentiation?

Gene expression

Which factors control phenotypic gene expression?

Transcription factors and environment

What is epigenetics?

Epigenetics is when gene expression is altered by chemical modifications, like DNA methylation, without changing the underlying nucleotide sequence.

Which modifications alter gene expression?

DNA methylation and histone modification

How can epigenetics cause cancer?

Altered cell division genes

Which diseases are caused by epigenetics?

Fragile X and Rett syndrome

What is a mutation?

Change in DNA sequence

What can cause mutations?

Replication errors and mutagens

What increases mutation rate?

Radiation and chemicals and viruses

What is a point mutation?

Single base change

What is a frameshift mutation?

A frameshift mutation is a genetic change caused by the insertion or deletion of nucleotides in a number not divisible by three, which alters the triplet reading frame of the mRNA sequence during translation.

What is a chromosomal mutation?

Alters chromosome segments

What is the result of a germ cell mutation?

Inherited by offspring

What is the result of a somatic cell mutation?

Not inherited

What is the aim of gene therapy?

Correct faulty gene expression

What does PCR stand for?

Polymerase chain reaction

What is the purpose of PCR?

Amplifies DNA segments

What does the PCR heating step do?

Separates DNA strands

What does the PCR cooling step do?

Primers anneal to template

Which enzyme extends DNA in PCR?

Heat-resistant DNA polymerase

Why is a heat-resistant enzyme used?

Survives denaturing temperatures