Download Intro. to Genetics

Objective: The student will be
able to understand genetics
Pg.
• Fill in the pamphlet as we go through
the PowerPoint
• When we are finished you can glue it
into your notebook.
• To do so place a strip of glue on the
top of the back page
Introduction to Genetics
Genetics = the study of heredity
• Gregor Medel
• The Father of Genetics
• carried out important studies of
heredity
• Heredity—the passing on of traits from
parents to offspring
• Trait- a specific characteristic that is
controlled by genes
• Ex. Eye color, hair color,
height
• Chromosomes
• Tightly coiled DNA
• Contain your genes
•Genes
•Sections of
DNA that
control your
traits
• Homologous Chromosomes
• Chromosomes that are the same size
and shape and carry the
same genes.
P
You get one from your mother and one
Short pea plant
Tall pea plant
from your father that match up.
1
F1
All tall pea plants
F2
3 tall: 1 short
• Alleles
• The different forms a gene can take.
• Represented by letters
• 2 Types of Alleles:
• 1. Dominant - Represented by a capital letter
(Ex. A)
• 2. Recessive - Represented by a lower-case
letter (Ex. a)
• Genotype
•The combination of two alleles that
represent the genetic make-up of a
individual.
3 Types of Genotypes:
• 1. Homozygous Dominant
• 2 identical alleles that are capitalized
(AA, TT)
• 2. Heterozygous
• 2 different alleles (Aa, Tt)
• 3. Homozygous Recessive
• 2 identical alleles that are lower-case
(aa, tt)
• Phenotype
•The observable physical
characteristic of an individual that
are the result of its genotype.
Principle of Dominance
• An organism with a recessive
allele for a particular trait will
exhibit that form only when the
dominant allele for the trait is
not present.
• Organisms with a heterozygous
genotype (Aa) will never exhibit
the recessive trait because it is
hidden (masked) by a dominant
allele.
• You try this one:
A
A
a
A
Question 1
The passing on of characteristics
from parents to offspring is
__________.
A. genetics
B. heredity
C. pollination
D. allelic frequency
The answer is B.
Genetics is the branch of biology that
studies heredity.
Question 2
What are traits?
Answer
Traits are characteristics that are inherited.
Height, hair color and eye color are
examples of traits in humans.
Question 3
Gametes are __________.
A. male sex cells
B. female sex cells
C. both male and female sex cells
D. fertilized cells that develop into
adult organisms
The answer is C.
Organisms that reproduce sexually produce
male and female sex cells, called gametes.
Question 4
Which of the following genotypes
represents a animal that is
homozygous dominant for a trait?
a. KK
b. Kk
c. kk
Question 5
Which of the following genotypes
represents a plant that is homozygous
recessive for height?
A. TT
B. Tt
C. tt