Genetics Flashcards
Who is Gregor Mendel
Austrian monk who used pea plants to learn about genetics.
Gregor Mendel’s 3 Laws of Inheritance
- Law of Dominance
- Law of Segregation
- Law of Independant Assortment
Mendel’s Experiments
- Had control over breeding
- Used only Purebreed plants
- Observed “either-or” traits
A cross
Mating of 2 organisms
F1: First Generation
P: Parental Generation
F2: Second Generation
Dominant Allele
Allele will always have that trait expressed (seen)
Recessive Allele
Allele will only have that trait expressed when the dominant allele is not present
Significance of Alleles
-Alleles have assigned letters
-Uppercase=Dominant
-Lowercase=Recessive
-Each individual has 2 Alleles (one from each parent)
-Homozygous: 2 of the same alleles (FF or ff)
-Homozygous: 2 different alleles (Ff)
Genotype
The actual alleles Inherited (FF, Ff, ff)
Phenotype
The physical characteristics or traits of an organism (freckles on face)
Gene expression
can be affected by the enviroment
Law of Dominance
a dominant (or strong Allele) will exxpress itself over a recessive (weak Allele)
Law of Segregation
When chromosomes separate in meiosis, each gamete (egg or sperm) will recieve only one chromosome from each pair
Law of Independent Assortment
-The Assortment of chromosomes for one trait doesn’t affect the assortment of chromsomes for another trait
-Therefore any combination of maternal and paternal chromosomes could be passed on because homologous chromosomes line up randomly during metaphase
Punnett Square
A diagram that shows the probability of inheriting traits from parents with certain genes
Monohybrid Cross
A cross between two organisms looking at one trait
DNA
-Deoxyribo Nucleic Acid
-Phosphate
-Sugar (deoxyribose)
-Nitrogen Base
-Double Helix
Organic Compounds
made of monomers
Nucleotides
Monomers of DNA
DNA Nucleotides (stand for)
G=Guanine
A=Adenine
C=Cytosine
T=Thymine
Job of DNA code
The molecular Bases (G, A, C, T) determine an organism’s DNA which codes for making proteins that works in the organism’s cells/bodies to determine their traits
Exceptions to Mendel’s Laws
Some alleles are neither dominant or recessive, and many traits are controlled by multiple alleles or multiple genes
Incomplete Dominance
-The heterozygous phenotype is somewhere between the two homologous phenotypes
-Neither Allele is completely dominant or recessive
-Ex: red and white flowers make pink flowers
Codominance
-Both traits are fully and seperately expressed
-Ex: red and white flowers make red and white speckled flowers
-Ex: blood type (AB blood type is fully A and fully B)
-Blood type is also an example of multiple alleles
Blood Type
-An example of codominance and multiple alleles
-Codominance: Blood type AB is fully A and fully B
-Multiple alleles: A Allele, B Allele, and I allele
Blood type Phenotype –> Genotype
-AB= IA IB
-A= IA IA, IA i
-B= IB IB, IB i
-O= ii
Multiple Alleles
-Having more than 2 Alleles for one gene
-Ex: Alleles for blood type
Polygenic Inheritance
-A trait produced by two or more genes
-Usually shows a range in phenotype
-Ex: Skin color, Eye color, Height, Personality
Epistasis
-When one gene overshadows all others
-Ex: Laborador Retriever fur colors, eye color, Albinism
Linked Genes
-Genes that are physically located on the same chromosome will be inherit together
-Ex: Blond Hair and Blue Eye, Red Hair and Freckles, Large Ears and Broad Nose
-Linked genes can only be: seperated or broken apart during crossing-over
Sex-Linked Traits (X chromosome)
-Contains many genes that affect many traits
-Linked to more than 100 genetic disorders
-Genes on the X chromosome are X-Linked
Sex-Linked Traits (Y chromosome)
-Carries few genes/determines if offspring is male
Sex-Linked Traits (definition)
-genes on sex chromosomes (X or Y)
-Females inherit gene as normal and principle of Dominance applies
-Males inherit the gene on the X, but not the Y.
-Because males have only one X, they express the trait whether it is dominant or recessive
-Ex: Color Blindness (Xb) Normal vision (XB)
mRNA
-Copies DNA’s code (instructions)
-Carries copy to the ribosomes (make proteins)
tRNA
-Carries Amino Acids to the ribosome and mRNA
Ribosomal RNA (rRNA)
-Makes up the ribsome
Transcription
-Purpose: Carry a copy of DNA’s code for a protein out of the nucleus
-Location: Nucleus
-Starts with: DNA
-Ends with: RNA
-Gene for a protein is copied
-Copy=mRNA
-mRNA will leave the nucleus to go to the ribosome
-3 base pairs=1 codon
-1 codon=1 Amino acid
Codon
a set of 3 nucleotides on the mRNA
Anticodon
“complementary” 3 nucleotides on tRNA
Translation
-Interpreting the RNA message into a protein
-Purpose: Read the code carried on the mRNA to make a protein
-Location: Ribosome
-Starts with: mRNA (with tRNA)
-Ends with: protein
-Protein is also called a polypeptide
-Transfer RNA (tRNA) carries amino acids from the cytoplasm to the ribosome
-mRNA carrying DNA instructions and tRNA carrying amino acids meet in the ribosomes
-Amino acids are joined together
