Dna, Genes And Chromosomes Flashcards
What does dna and rna do
Both carry information
DNA holds genetic information
RNA transfers genetic information from dna to ribosomes made of rRNA and proteins
What is the structure of dna
Polymer of nucleotides
Deoxyribose, a phosphate group and one of the organic bases: a, t, c, g
Adenine and guanine both have double ring structures
What is the structure of rna
Polymer of nucleotides
Ribose, phosphate group and one of the bases: a, u, c, g
T,u and c all have single ring structures
What is the structure of a dna molecule and how does it differ to an rna molecule
Double helix structure composed of 2 polynucleotides joined by hydrogen bonds between complementary bases, whereas rna is a shorter polynucleotide chain
What is the genetic code
Triplets of bases
What is a codon
When each triplet of bases codes for an amino acid
How is a polypeptide chain formed
Amino acids joined together by peptide bonds
What is a gene
A sequence of amino acids that codes for a specific polypeptide chain.
What are introns
Non coding dna
What are exons
Coding sections of dna
What are 3 features of the genetic code
Non overlapping
Non coding
Degenerate
What does non overlapping mean
Each triplet is only read once and don’t share any bases
What does non coding mean
Genes are separated by non coding bases that do not making proteins
What does degenerate mean
More than one triplet codes for the same amino acid, which reduces the number of mutations
What dies the genetic code contain
Start and stop codons
What is dna like in eukaryotic cells
Found in the nucleus
Long and linear
Associated with proteins to make histones to make chromosomes
What is dna like in prokaryotic cells
Short and circular
Not associated with proteins
What is a homologous pair of chromosomes
Two chromosomes that carry the same genes
What is an allele
An alternate form of the same gene
What is mRNA
A long single strand created in transcription in which the base sequence the complementary to dna
What is rRNA
Small molecule made up of 80 nucleotides
Folded into a clover shape
Has an anticodon specific to the amino acid it attaches to
What are the steps of transcription
1: hydrogen bonds are broken by dna helicase which unzips the 2 strands of dna
2: one strand of dna is used as a template
3: free nucleotides join up with their complemtary pairs and are held by phosphodiester bonds made by rna polymerase
4: in eukaryotic cells splicing occurs, where introns are removed
What is the proscess of translation
1: ribosomes binds to mRNA
2: ribosomes moves to start codon
3: a tRNA with a complementary anticodon to mRNA codon forming a hydrogen bond
4: carrying a specific amino acid
5: ribosome can fit 2 tRNA molecules
6: the amino acid joined together by peptide bonds in a condensation reaction using atp
7: ribosome moves to next codon and process repeats with a polypeptide produced
What happens in a genetic mutation
A mutation is any change to the dna base sequence
- the mutation changes the amino acid coded for
- this changes the primary structure, sequence of amino acids
- this changes the tertiary structure
- as the h, ionic, and disulfide bridges form in a diff place
- this changes the 3d shape and therefore 3d function
