Genetics Flashcards
What plant is Gregor Mendel use and why?
Pea plants because they are easy to grow, has quick germination time, controllable pollination, and traits are easy to observe
Gregor Mendel
Father of genetics and referred to inheriting genes as “factors”
Pollination
Fusion of the pollen and egg to form a seed
Alleles
Different forms of the gene for a specific characteristic. Located at the same point on homologous chromosomes( ex. Tall vs small plants)
Dominant
The trait expressed when two different allele are present, show by capital letter
Recessive
Gene that is present but not expressed , shown by lowercase letters
Genotype
Genetic makeup of an individual ( ex.Tt)
Phenotype
Trait that appears in the individual
Heterozygous
Hybrid, two allele for trait that are different(ex. Tt)
Homozygous
Pure, two alleles for a trait are the same(ex. TT)
Law of dominance
Heterozygous individuals will express the phenotype of the dominant allele(ex. Tt will be a tall plant)
Test cross
Cross individual with a pure recessive individual. If some offspring show recessive trait, you have heterozygous individual. If all offspring show dominant trait, you have a homozygous dominant trait
Law of segregation and recombination
Meiosis -allele separate Fertilization: allele combine again ( Tia is why offspring can express a different phenotype VARIATION)
Law of independent assortment
Traits are inherited independent my of each other (ex. Seed color and seed shape)
Incomplete dominance
(Aka blending ) only partially dominant, intermediate phenotype (ex. Red flowers x white flowers =pink )
Co dominance
Two dominant alleles are equally expressed (ex. White cattle x red cattle = roan cattle)
Sex determination
Determined by sperm X + Y= sex chromosome (not homologous )
Sex linked traits
Disorder linked to the X chromosome (ex.hemophillia and color blindness) most common in males…. Only need to get it from mom(x)
Carriers
Female that has the trait in only one x , does not express trait, 50% chance of passing of trait in to son
Gene linkage
Genes for two different traits are locate in the same chromosome, can be inherited together, the further apart on a chromosome (freckles and red hair), the less likely to be inherited together
Crossing over
Exchange of genetic material during synapsis , variation in gamete
Multiple alleles
More than two allele for a given trait (ex. Blood type- type a and b are codominant over type o)
What is the phenotypic ratio of the F2 generation ?
1:2:1
What are nucleotides?
Building blocks for nucleus acids
DNA
Deoxyribonucleic acid, Watson and Cricks double helix
Nitrogenous bases
Purines and pyrimidines
Purines
Guanine and adenine each have tow linked rings of atom
Pyrimidines
Cytosine, thymine, and uracil each have a single ring
RNA vs DNA: number of strands
RNA 1 DNA 2
RNA vs DNA: 5 carbon sugar
RNA ribose DNA deoxyribose
RNA vs DNA: nitrogenous bases
RNA AUCG DNA ATCG
Helicate
Enzyme that breaks hydrogen bonds holding the two DNA strands together
DNA polymerase
Only add nucleotides to the 3’ end
Leading strand
DNA strand that is read in the 3’ to 5’ direction but is synthesized in the 5’ to 3’ direction in a continuous manner
Lagging strand
Made in pieces called Okazaki fragments
DNA ligase
Links together Okazaki fragments
Gene
Segment of DNA that codes for making a protein
Translation
mRNA -> amino acid sequence (ribosome) tells what gene means
Transcription
DNA -> mRNA (nucleus) “writes” the genes
Codon
Triplet of nucleotides on mRNA that codes for one amino acid
One Gene- One Polpeptide
One gene on DNA codes for one polypeptide chain, some proteins composed of 2 or more chains, proteins have a quaternary structure, hav has 4 p chains
3 stages of transcription
Initiation, elongation , and termination
Initiation
RNA polymerase binds to DNA promoter, which is a specific nucleotide sequence in DNA sat the start of a gene instructs RNA polymerase where to start transcribing RNA , ex. TATA box
Elongation
RNA polymerase moves along DNA , untwist the DNA one turn about 1” bases at a time, adds nucleotides to the 3’ end of the growing RNA ,60 nucleotide per sec
Termination
Termination site on DNA (ex AATAAA) signals RNA polymerase to stop transcription
Poly-AAA tail
up to 200 bases long is attached at the 3’ end
Guanosine tri phosphate cap
Is added to the 5’ end.. Acts as an “attach here” sign for the ribosome, two ends may protect the molecule from degradation (being broken down)
Gene slicing
In eukaryotes , mRNA is modified before leaving the nucleus
Intros
The non-coding sequence of genes that is taken out before translation (want to get out)
Extrons
The coding region of a eukaryotic gene that is EXPRESSED
Ribosome
Made up of two subunits, in nucleoli, contains ribosomal RNA and protein, has 3 binding sites (1 for attachment of mRNA and two for tRNA )
P site
Holds the tRNA attached to the growing polypeptide chain
A site
Holds the tRNA attached to the next amino acid to be added to the chain
4 stages of translation
Codon recognition , peptide bond formation, elongation of polypeptide via movement ( a and p site) , termination stop codon at A site on ribosome (ex. UAA)
Light and chlorophyll
No light, the no chlorophyll production
Temp and hair color
At low temp the hair in Himalayan rabbits will grow back darker
Identical twin studies
Compare those who were separated at birth and those who were not