DNA and genetic diseases Flashcards
What is DNA an abbreviation for?
Deoxyribonucleic acid
Name the components of a DNA nucleotide.
Deoxyribose
Phosphate
Nitrogenous organic base - guanine, cytosine, adenine or thymine
Name the type of bond formed between complementary bases
Hydrogen bond
Name the pyrimidine bases
Cytosine and Thymine
Name the purine bases
Guanine and adenine
How many rings structures are present in a purine base
Two
How many ring structures are present in a pyrimidine base?
One
How many ring structures are present in a pyrimidine base?
One
Describe the shape of a DNA molecule
Double helix - two antiparallel polynucleotide chains held together by hydrogen bonds between specific complementary base pairs.
The two polynucleotide strands in DNA are antiparallel. True or false
True
Give the specific complementary base pairs found in DNA.
Guanine and cytosine
Thymine and adenine.
Name the process involved in the replication of DNA
Semi-conservative replication
What is the function of DNA helicase?
Breaks the hydrogen bonds between the complementary bases in the helix, unwinding the DNA and exposing unpaired bases.
Describe the process of DNA replication
Unwinding of double helix
Breaking bonds between complementary bases
Catalysed by DNA helicase.
Diffusion of new DNA nucleotides to exposed bases on template strands and base pairing.
Hydrogen bonds form between complementary bases
Formation of bonds between adjacent nucleotides in the new strand of DNA.
Catalysed by DNA polymerase.
Name the enzyme responsible for breaking the hydrogen bonds between the 2 strands of DNA?
DNA helicase
Name the enzyme used to catalyse the production of bonds between adjacent nucleotides
DNA polymerase
Give two differences between a DNA and RNA nucleotide.
DNA contains deoxyribose whereas RNA contains ribose.
DNA contains thymine whereas RNA contains uracil.
How are the 2 strands of DNA that make up the double helix held together?
Hydrogen bonds between complementary nitrogenous bases
What is meant by ‘semi conservative’ DNA replication?
Each new DNA molecule contains an original and new strand of DNA
Describe the role of DNA helicase in transcription
DNA helicase breaks hydrogen bonds between the bases in the helix, unwinding the DNA and exposing unpaired bases.
RNA polymerase links to the template strand of
Describe the role of RNA polymerase in transcription
DNA polymerase links to the template strand of DNA, inserting mRNA nucleotides one at a time, according to the rules of complementary base pairing and forming bonds between them.
How many bases are needed to code for one amino acid on the DNA?
The code is 3 bases long (called a triplet)
Give the name for three bases on the mRNA that code for one amino acid
Codon
What is a stop sequence on the DNA?
Indicates the end of the gene. RNA polymerase leaves the DNA and transcription stops
How many attachment sites for tRNA are present on the ribosome?
Two
How many sub-units are there in a ribosome?
Two
Which sub-unit does mRNA attach to on the ribosome?
Small sub unit
Which sub unit does tRNA attach to on the ribosome?
Large sub unit
What doe tRNA molecules carry to the ribosome?
A specific amino acid
Describe the process of translation.
Ribosome binds to the start codon on the mRNA.
tRNA molecules bind to the ribosome through codon-anticodon interactions.
A peptide bond forms between 2 amino acids.
The ribosome moves along the mRNA one codon at a time.
This continues until the stop codon is reached
The genetic ode is linear and non-overlapping. What does this mean?
Linear - one continuous sequence
Non-overlapping - bases are read in sequence.
The genetic code is degenerate. What does this mean?
Several triplets can code for the same amino acid.
The genetic code is universal and unambiguous. What does this mean?
The genetic code is the same in all living organism’s
Cystic fibrosis is an inherited disease. What does this mean?
Alleles pass from one generation to the next. It caused by a mutation on the DNA
Some inherited diseases are recessive. What does this mean?
Individual must be homozygous for this condition. Must have inherited recessive alleles from both parents
Polydactyly is a dominant condition. What does this mean?
An individual only needs one dominant allele to show polydactyly
