Module 1 Flashcards
Study of variation and heredity
Genetics
Similarities and differences among organisms
Variation
How characteristics are transmitted through generations
Heredity
Functions of Genetic Information
- Directs Cellular Function
- Determines external appearance
- Serves as link between generations in every species
Genes are Particulate Factors
Gregor Mendel
Discovered Nucleic Acids
Friedrich miescher
Chromosomes are hereditary units
Walter Sutton
Genes lie on chromosomes
Thomas Hunt Morgan
Chromosomes are linear arrays of genes
Alfred Sturtevant
Mutations are physical changes in genes
Hermann Muller
Recombination occurs by crossing over
Harriett Creighton & Barbara McClintock
A gene codes for a protein
George Beadle & Edward Tatum
DNA is the genetic material
Oswald Avery, Colin MacLeod, and Maclyn McCarty
First protein sequenced
Frederick Sanger
DNA is a double helix
James Watson & Francis Crick (AND Rosalind Franklin)
DNA replicates semiconservatively
Matthew Meselson & Franklin Stahl
Genetic code is triplet
Marshall Nirenberg & Heinrich Matthaei
DNA can be sequenced
Frederick Sanger, Allan Maxam & Walter Gilbert
Haemophilus influenzaegenome sequenced
Institute of Genomic Research
Human genome sequenced
Human Genome Project
4 FIELDS OF GENETICS
- Transmission Genetics
- Cytogenetics
- Molecular Genetics
- Population Genetics
Patterns of inheritance are determined through planned breeding experiments
Transmission Genetics
Study of the cellular or physical basis of heredity (chromosomes)
Cytogenetics
Characterization of the chemical nature of the genetic materials (DNA and RNA) as well as the mode by which they bring about the traits they control
Molecular Genetics
Describes the behavior of genes in large groups of individuals with passage of time
Population Genetics
6 METHODS OF STUDYING GENETICS
- Planned experimental breeding
- Pedigree analysis
- Statistical analysis
- Twin study
- Karyotyping
- DNA testing/profiling
discrete heritable units that are passed
on from parent to offspring
Genes
alternative forms of the same gene; found in chromosomes
Alleles
Differentiate Dominant and Recessive Allele
Dominant allele–fully expressed
Recessive allele–has no noticeable effect in the presence of the dominant allele
particular site in the chromosome where an allele is found
Locus
matched pair of chromosomes in a diploid cell
Homologous Chromosomes
Characteristics of a genetic material
- Stable – does not easily denature (940 C)
- Replicable – sequence (and information) can be
copied - Translatable – sequence (and information) can
be converted into a different
language (proteins) - Mutable – can be changed to yield variations
Evidence favoring DNA as the genetic material
- Transformation experiments by Griffith (1927)
- Transformation experiments by Avery, MacLeod and McCarty (1944)
Why are AT/AU pairings weaker than GC base pairs.
GC has 1 more H-bond than AT/AU
Types of RNA
- Transfer RNA (tRNA)–carries amino acids
- Ribosomal RNA (rRNA)–binds with proteins to form ribosomes
- Messenger RNA (mRNA)–template for protein synthesis
- Micro RNA (miRNA)–regulates gene expression
Transcription differs from DNA replication in 3 ways:
1.Only a small region of one DNA strand is used as a
template.
2. RNA polymerase instead of DNA polymerase for nucleotide addition.
3. Results in a single-stranded RNA.
Transcription components
1) RNA polymerase and associated proteins
2) DNA sequence
a) promoter
b) gene
DNA strand from which RNA is transcribed
Template/Antisense Strand
Untranscribed strand; Identical in sequence to transcribed RNA
Coding/Sense strand
Types of RNA polymerases in Eubacteria
Only 1 type used for all types of RNAs
Types of RNA polymerases in Archaea
Several types but not studied
Types of RNA Polymerases in Eukarya
1.RNA polymerase I–18S, 5.8S and 28S rRNA
2. RNA polymerase II-precursor mRNA, miRNA
3. RNA polymerase III–tRNA, 5S rRNA, miRNA
Conformation of the tRNA anticodon loop permits flexibility at the 1stbase of the anticodon.; Hypothesis that explains why differences at third codon can occur but leave it unaffected.
Wobble Hypothesis
Function of mRNA
Template for protein synthesis
Function of tRNA
Carries Amino Acids
Function of rRNA
Binds with proteins forming ribosomes
Difference between Prokaryote and Eukaryote central dogma
Prokaryote: Replication, transcription, and translation occur in cytoplasm and can occur at the same time
Eukaryote: Step-by-step due to different locations for each step
Occurs during the Synthesis (S) phase of cell cycle
Single chromatid thread → two chromatids
Each daughter cell must have a copy of a sister chromatid
Semiconservative
Produces daughter double strands made up of an old and new strand
Occurs in the 5’ to 3’ direction
The orientation of the DNA template is 3’ to 5’ direction
Replication
Causes Okazaki Fragments
Lagging strand; transcription requires multiple promoters.
Biosynthesis of RNA from DNA template
Transcription
Enzymes involved in replication and their function (3):
Helicase - unwinds the double helix by disrupting H-bonds
DNA polymerase - joins the sugar phosphate backbone between nucleotides
DNA ligase - connects Okazaki fragments via formation of phosphodiester bonds
Stages of Transcription
- Initiation
- RNA pol and associated proteins bind to the promoter region - Elongation
- DNA unwinds as H bonds break
- Free nucleotides of the RNA pair with complementary DNA bases
- RNA sugar-phosphate backbone forms (aided by RNA pol) - Termination
- H bonds of untwisted RNA+DNA ladder break, freeing the new RNA
Sites of large ribosomal subunit
E site - exit site
P site - Peptidyl-tRNA binding site
A site - Aminoacyl-tRNA binding site
Hep hep?
Hooray
