DNA Structure, Mutation and Inheritance 2.5, 2.12, 2.13 Flashcards
What is the function of DNA?
It’s a store of genetic information containing all the instructions an organism needs to grow and develop
What is the function of RNA?
Transfer genetic information from DNA to ribsosomes
What organelle is made from RNA and proteins?
Ribsosomes
Describe a mononucleotide
A pentose sugar (5 carbon) attached to a nitrogenous base and a phosphate group
Define DNA/RNA
Polynucleotides composed of mono nucleotides linked by condensation reaction
Describe the structure of a DNA molecule
Double helix with two polynucleotide chains consisting of a sugar phosphate backbone held together by hydrogen bonds between the complementary bases
What is a polynucleotide
A polymer of mononucleotides
How are mononucleotides joined - what is the byproduct?
Condensation reaction between the phosphate of one mononucleotide and the sugar group of another
Water is a byproduct
How many hydrogen bonds between A and T bases
A and T = 2 hydrogen bonds
C and G = 3 hydrogen bonds
What is a mutation?
A change to the base sequence of DNA that can be causes by errors during DNA replication
Name the 5 types of mutation
Substitution Deletion Insertion Duplication Inversion (sequence of bases is inverted)
How can a mutation affect a protein?
The order of DNA bases determines the order of amino acids which makes up the primary structure of a protein and thus therefore could be altered, changing the final 3D shape of the protein
How many possible mutations are thought to cause CF?
Over 1000
Define a ‘gene’
A sequence of bases on a DNA molecule that codes for a protein
Define ‘allele’
A different version of a gene. Most plants and animals have two copies of a gene, one from each parent
Define ‘genotype’
The alleles a person has eg. BB Bb bb
Define ‘phenotype’
The physical characteristics expressed by an organism eg. Brown eyes
Define ‘dominant’
Allele which is displayed in the phenotype even if only one copy is present
Define ‘recessive’
Allele whose characteristic is only displayed in the phenotype if two copies are present
Define ‘incomplete dominance’
When the trait from the dominant allele isn’t completely shown over the trait from the recessive allele = both alleles influence the phenotype
eg. Snapdragons have alleles for red (RR), white (rr) and pink (Rr)
Define ‘homozygote’
An organism that carries two copies of the same allele for a certain characteristic eg. BB or bb
Define ‘heterozygote’
An organism that carries two different alleles for a certain characteristic eg. Bb
Define a ‘carrier’
If a recessive allele causes disease, a carrier is someone that has one recessive and one dominant allele (heterozygous)
What is mono hybrid inheritance?
The inheritance of a single characteristic controlled by different alleles
What is a genetic pedigree diagram?
Show an inherited trait in a group of related individuals
When will a person have CF?
If they’re homozygous recessive for the cf allele
What is cystic fibrosis caused by?
A mutation in the gene that codes for the CFTR protein (a channel protein)
What does the CFTR channel protein do?
Transpires chloride ions out of cells and into mucus causing water to move in by osmosis making the mucus watery
What happens to the mucus if there is a mutation in the CFTR channel protein?
Makes it less efficient at transporting chloride ions out of the cell so less water moves out by osmosis causing it to be sticky and thick
