Biology Ch. 2 Flashcards
Homologous Chromosomes
Pair of chromosomes (one maternal and one paternal) that contain the same genes in the same locations.
Hemizygous
Having one copy of a gene instead of two (male sex chromosomes are XY).
Mendel’s Laws
Segregation: gametes only carry one allele for each gene.
Independent Assortment: homologous pairs separate independently from one another.
Dominance: dominant alleles mask recessive.
Incomplete Dominance
More than one dominant allele, neither is completely dominant.
Heterozygote will be a blend, red + white= pink
Codominance
Both inherited dominant alleles are completely expressed.
Red + white = red and white speckled.
Epistasis
One gene’s expression affects the phenotypic expression of another.
If you have a gene for baldness, the gene for hair color is not shown/expressed.
Pleiotropy vs. Polygenic Inheritance
Pleiotropy: single gene affects multiple phenotypic traits.
PI: multiple genes affect one phenotype. Usually a spectrum of outcomes; skin tone, height.
Penetrance
Probability an organism with a genotype will express the associated phenotype.
Complete would be 100%.
X Inactivation
In females, one X chromosome will be methylated and inactivated, called a Barr Body.
Example: calico fu in cats.
Chromosome Translocations
2 chromosomes swap segments; can cause size differences.
Called substitution if it is a one-way donation.
Helicase
Topoisomerase
Single Stranded Binding Proteins
H: separates DNA strands
T: relieves tension on DNA by unwinding by breaking and rejoining strands.
SSBPs: bind to ss DNA near rep fork to keep strands apart.
Primase
DNAP III
DNAP I
Ligase
P: creates RNA primer needed for rep initiation.
DNAPIII: synthesizes DNA in 5’ to 3’ direction.
DNAP I: removes RNA primer after replication and replaces with DNA.
L: seals gaps in phosphodiester bonds.
Transcription Initiation, Elongation, and Termination
I: RNAP binds to promoter (TATA) with help of TC factors.
E: RNA is synthesized 5’-3’ using antisense strand as template.
T: RNAP meets AAA rich region and detaches.
RNA Splicing and Alternative Splicing
RNA: removing introns and connecting remaining exons.
AS: combining exons in different ways to code for multiple proteins.
Translation Initiation, Elongation, Terminatioin
I: small subunit binds to mRNA, methionine tRNA attaches to start codon, large subunit binds.
E: tRNAs carrying AAs enter A site, pp chain from P site attaches to tRNA in the A site, then it shifts to P site while the old tRNA exits through E site.
T: stop codon enters A site and release factors cause everything to disassemble and release peptide chain.
Silent, Missense, and Nonsense Mutations
S: codon is changed but AA is unchanged.
M: substitution causes AA change.
N: substitution changes to a stop codon.
Genome
Transcriptome
Proteome
G: complete genetic information of an organism.
T: set of all RNA molecules that a cell can produce.
P: complete set of proteins in an organism that are expressed.
Gene Density
Percentage of genome consisting of coding genes.
Prokaryotes genes are more dense than eukaryotes because they don’t have introns.
The vast majority of the human genome is noncoding.
Temperature-Dependent Sex Determination:
Pattern I and Pattern II
Pattern I: males develop in cold, females develop in warm (turtles).
Pattern II: females develop in hot/cold, males develop in medium (crocodiles).
DNA Methylation and Histone Acetylation
Methylation: stops gene expression by condensing into heterochromatin.
Acetylation: increases expression by loosening into euchromatin.
RNA World Hypothesis
Self replicating RNA molecules were precursors to life.
RNA can store genetic info like DNA and can catalyze chemical reactions like enzymes.
Light Microscope
Scanning Electron Microscope
Transmission Electron Microscope
Fluorescence Microscope
LM: visible light to view thin sample; need to stain; kills cells.
SEM: used to view Surface of 3D objects with high res; kills sample.
TEM: thin cross sections of internal structures at high magnification; kills sample.
FM: fluorescent probes that bind to specific things; can be used on live cells.
Order of pellet formation in Centrifugation
Largest/most dense form pellet first.
Nucleus > mitochondria/chloroplasts > ribosomes.
Microarray
Used to monitor expression of large groups of genes across a genome.
Southern Blot
Northern Blot
Western Blot
S: DNA
N: RNA
W: Protein
Pasteur’s Experiment
Disproved spontaneous generation.
Curved neck flask experiment.
Griffith’s Experiment
Proved transformation.
Made a non-virulent bacteria virulent by exposing it to virulent bacteria DNA.
Avery-MacLeod-McCarty
Found DNAse prevented transformation.
Used similar methods to Griffith.
Hershey and Chase
Showed phages used DNA for genetic material.
Used radioactively labeled P (DNA) and S (proteins).
Meselson and Stahl
Proved semiconservative replication.
Used 2 isotopes of N in nucleotides and found that daughter strand contained one of each.
Gurdon
Proved fully differentiated cells have full genome.
He removed a nucleus from a frog’s intestinal cell and was able to make a full individual out of that DNA.
