Chapter 1 Flashcards
Genetics
- investigation of genotypic and phenotypic variation among organisms
- how this variation is inherited
- how they are linked to each other
- how they evolve
Genetics historical overview
- selective breeding of plants and animals
1590
- Hans and Zacharias Jensen invented the microscope
1866
- Mendel quantitative mechanism of phenotypic inheritance
1900
- botanists Correns, Vries, and Tschermak replicate Mendel’s results
1909
- Morgan et al rediscover Mendel’s laws using fruit fly mutants
1911
- White eye pheno in fruit flies determined to be a sex-linked trait
1915
- Sturtevant first genetic map (using f flies)
cont idk if i should add
Gene
a region of DNA with a biological function
Allele
the alternative forms of a gene
Locus
specific site on a chromosome occupied by an allele/gene
Homologs
two chromosomes (homologous chromosomes) which may carry the same or different alleles for the same loci
Genotype
combination of alleles at one or more loci an individual possesses
Three fields of genetics
Mendelian genetics
- transmission of traits across generations
Molecular genetics
- investigates the inheritance, expression, and variation of nucleic acids and proteins
Evolutionary genetics
- examines the origins and genetic relationships between organisms and the evolution of genes and genomes
Watson and Crick
discovered DNA structure
- foundation for molecular genetics
- two nucleotide polymers forming a double helix
DNA structure
- ACTG in DNA
A-T, C-G
polar strands and are antiparallel
3 components of nucleotides
- deoxyribose sugar
(pentose) - nitrogenous base
- phosphate(s)
Nucleotide bonding
1’ carbon covalently bonded to nitrogenous base
5’ carbon phosphodiester bond with
- phosphate and
- 3’ OH of adjacent nucleotide
Chargaff’s rule
know one sequence = can predict complementary strand
- %C = %G
- %A = %T
Is DNA replication conservative
how does it occur
semi-conservative
- complementary strands separate
- each strand is a template for the synthesis of a new daughter
always in the 5’ to 3’ direction
one synthesized towards replication fork, one away
Central dogma of biology
Whose idea
describes the flow of hereditary information
idea from Francis Crick
DNA
–> transcription
RNA
–> translation
Protein
Transcription
DNA to single-strand RNA
template to coding strand
coding strand = same as nontemplate strand but U instead of T
Translation
mRNA to polypeptide
= a.a.s joined by covalent peptide bonds at the ribosome
makes a protein when folded
- ribosome translates 5’ to 3’ along mRNA
Codons
three nucleotides = one codon = one amino acid
start codon usually AUG
The genetic code and codons
64 possible triplet codons:
61 a.a.s
3 stop codons
4 nucleotides x 4 x 4
20 amino acids
- multiple codons can lead to the same amino acid
Point of redundancy in the genetic code
- buffers against point mutations
Silent mutations
- mutations that don’t affect the translated peptide
