Class Notes (838,995)
Canada (511,159)
Biology (6,826)
Biology 1001A (1,727)
Tom Haffie (1,170)
Lecture 7

Lecture 7-8.docx

10 Pages
Unlock Document

Biology 1001A
Tom Haffie

October 4, 2011 Biology Chapter 11-12.2 (Lecture 7-8) Pedigree • Chart that shows all parents and offspring for as many generations as possible , the sex of individuals in the different generations, and the presence or absence of a trait of interest Gene vs. Allele vs. Locus ABO Blood Type Alleles • A vs. i  A is dominant • A + B  Co-dominance, both expressed • Red blood cells have no nucleus when they mature EVOLUTION DETERMINES THE FREQUENCY OF ALLELES. HAS NOTHING TO DO WITH DOMINANCE (NATURAL SELECTION) White blood cells display ‘tissue typing’ antigens • Tissue typing antigens are coded by Histocompatibility Locus (HLA) o Several different genes in a cluster on Chromosome 6, several alleles for each gene- each giving rise to a different cell surface protein o Each distinct collection of alleles is called a haplotype o Each person, therefore, expresses two HLA haplotypes o White blood cells are easiest tissue to screen Tetragametic Chimerism • Arise from 2 separate fertilizations • NOT a hybrid (single fertilization) • The cells themselves did NOT fuse together, they just made one person 11.1- The Beginning of Genetics: Mendel’s Garden Peas • Important terminology o Self-fertilize (self-pollinate)-sperm nuclei in pollen produced by anthers fertilize egg cells housed in the carpel of the same flower o Cross-Pollination- Fertilization of one plant by another plant o True-Breeding- Individual that passes traits without change from one generation to the next o F1 Generation- The first generation of offspring from a genetic cross o F2 Generation- The second generation of offspring from a genetic cross o Dominance- the masking effect of one alleles over another o Homozygote- An individual with two copies of the same allele o Heterozygote- An individual with two different alleles of a gene o Genotype- the genetic constitution of an organism o Phenotype- the outward appearance • Gregor Mendel’s experiments with garden peas (1860s) o Garden peas offered simple cultivation, clearly defined, true breeding, characters (flower colour or seed shape) and an opportunity to make controlled pollinations o Trait- A variation in a character, such as purple or white flower colour o Mendel showed that traits are passed from parents to offspring as hereditary factors (genes and alleles) in predictable ratios and combinations  DISPROVING BLENDED INHERITANCE Mendel’s crosses with seven different characters in peas, including his results and the calculated ratios of offspring • In all cases, he observed a uniform F1 generation, in which only one of the two traits was present. In the F2 generation, the missing trait reappeared, and both traits were present among the offspring. • The trait present in the F1 generation was present in a definite, predictable proportion among the offspring • Made an explanatory model o Variation in traits due to different alleles o Organisms inherit two alleles for each trait o Dominant alleles determine appearance of heterozygotes o Alleles segregate randomly into gametes • Dominance o Dominant alleles are NOT most common o Do NOT inhibit expression of recessive alleles o Determines Phenotype • Monohybrid crosses can be explained if: 1. The genes that govern genetic characters occur in pairs in individuals 2. If different alleles of a gene are present in a pair within an individual, one allele is dominant over the other 3. The two alleles of a gene segregate and enter gametes single • Dihybrid o Two genes, two alleles, and independent assortment o Only get the 9:3:3:1 ratio if the genes are on different chromosomes • Product Rule in Probability o Individual probabilities are multiplied • Sum Rule in Probability o Applies when several different events all give the same outcome o Probability that either event A, B or C will occur equals probability of event A + probability of B + probability of C • To determine if an individual is heterozygous or homozygous for a dominant allele o Testcross between an F1 heterozygote and a homozygous recessive parents • Independent Assortment- The alleles of the genes that govern the two characters segregate independently during formation of gametes. o Particular chromosome could line up on the left or right. Collectively, the organism makes four kinds of gametes • Walter Sutton was the first person to note the similarities between the inheritance of genes and the behaviour of chromosomes in meiosis and fertilization. Thes
More Less

Related notes for Biology 1001A

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.