Genetics Flashcards
Non-Overlapping
Each base is part of only one triplet
Degeneracy
More than one codon codes for a single amino acid
What is a codon?
Triplet/three bases on mRNA that codes for an amino acid
Describe the process of transcription
1) Hydrogen bonds between DNA bases break
2) Only one DNA strand acts as template strand
3) Free RNA nucleotides align by complementary base pairing
4) RNA polymerase joins adjacent RNA nucleotides together via phosphodiester bonds
5) Pre-mRNA is spliced (to form mRNA) (Introns are removed)
Describe the process of translation
1) mRNA attaches to ribosome
2) tRNA anticodons bind to complementary mRNA codons
3) tRNA brings a specific amino acid
4) Amino acids join by peptide bonds using ATP
5) tRNA released after amino acid joins to polypeptide
6) Ribosome moves along the mRNA to form the polypeptide
Ribosome structure
RNA and protein
Describe the effect of a gene mutation
1) Change in base/nucleotide
2) Results in the formation of a new allele
Gene mutation with no effect
1) Triplets code for same amino acid
2) Occurs in introns/non-coding sequence
What is the genome
All the DNA in a cell
What is the proteome
The full range of different proteins that a cell can produce
mRNA compared to tRNA
1) mRNA does not have hydrogen bonds/base pairing whereas tRNA does
2) mRNA is linear / straight chain, tRNA is cloverleaf shaped
3) mRNA has more nucleotides
4) Different mRNAs have different lengths, all tRNAs are similar in length
Pre-mRNA compared to mRNA
1) Introns present in Pre-mRNA
2) Pre-mRNA undergoes splicing
What are homologous chromosomes?
Two chromosomes that carry the same genes
What is crossing over?
1) Pairs of homologous chromosomes line up next to each other
2) The chromosomes twist around each other
3) Pressure causes sections of the chromosomes to break off
4) Reshuffling causes genetic variety
What is independent segregation?
When cells divide during meiosis, homologous chromosomes are randomly distributed to daughter cells.
Compare mitosis and meiosis
1) Mitosis has one division, meiosis has two.
2) Daughter cells are genetically identical in mitosis, different in meiosis
3) Two cells produced in mitosis, Four cells produced in meiosis
4) Diploid to diploid/haploid to haploid in mitosis. Diploid to haploid in meiosis
5) Both create new combination of alleles
