Summary genetics

LESSON 3 BIO 05 - GENETICS


TERMS  Genotype
 actual genetic make up,
 Gregor Johann Mendel
symbols
 introduced the theory of
 Dominant
inheritance based on pea
 Trait always appear in the
plants
offspring of parents with
 Heredity
contrasting traits, symbol
 is a result of discrete units
is capital letter
of inheritance and every
 Recessive
single unit is independent
 trait that does not appear
in action in an individual’s
in the offspring of parents
genome
with contrasting traits,
 Inheritance
symbol is lowercase letter
 depends on the passing on
 Monohybrid
of genes
 Cross involving one
o each individual
character
inherits a pair of  Dihybrid cross
gene from each  Cross involving 2
parent
characters
 Genes
 F1 vs. F2
 segment of DNA  Offspring of P
 produce 1 protei
 Offspring of F1
 Mendel’s factor  true breeding- parental
 Alleles
generation
 alternative form of a gene  offspring have same traits
 Character as parents when parents
 inherited feature ( flower self fertilize
color)  P1, homozygous, pure breeding
 Trait  Hybrid
 variant of a characteristics o offspring from a
( white or red flower
cross of parents
 Homozygous
differing in one or
 2 alleles for a particular
more
characteristics are
characteristics-
identical
heterozygous
 Heterozygous
 Backcross
 Two alleles for a particular
 cross with a parent or
characteristics are
parent type = Tt x TT, tt
different
 Phenotype
 effects of a gene,
description of appearance
 Testcross

,LESSON 3 BIO 05 - GENETICS


 cross unknown genotype Locus
with a homozygous
 Position on a chromosome where
recessive
 Used to determine if a
dominant trait is
homozygous or
heterozygous
 T__ x tt
 Intercross
 1 factor
o cross of two
heterozygotes,
o PR=3:1, GR: 1:2:1
 2 factor
a gene is located
o cross of two
heterozygotes
involving two
Dominant vs. recessive
characters
o PR= 9:3:3:1  Allele
 any 2 or more related
What is gene?
genes of a trait
 Operational region of the  Dominant alleles
chromosomal DNA  expresses its effect over
 Part is transcribed into a another allele
functional RNA at the correct  masks or hide the
time and place during recessive allele in the
development heterozygous organism
 Composed of transcribed region  Recessive allele
and adjacent regulatory regions  masked or hidden in a
heterozygous individual by
the presence of a
dominant allele
 Dominance does not determine
the relative frequency of a gene
in a population

, LESSON 3 BIO 05 - GENETICS


Homologous chromosomes Law of segregation
 Allele pairs separate and each
genes goes into a different
gamete
 Occurs during meiosis
 Applied in monohybrid cross
 Monohybrid cross a cross
between 2 individuals involving 1
character

Homozygous vs. heterozygous  Observes inheritance pattern of
one character
Law of Dominance
 When mating occurs b/w 2
organisms of different traits, each
offspring exhibits the trait of one
parent only
 If dominant allele is present
dominant trait will result while the
recessive trait will only result if
both alleles are recessive


Genotype vs. Phenotype
 Phenotype
 visible appearance
 Genotype
 genetic constitution
Mendel’s 7 pea traits



Pure breeding
 Parents are either homozygous
dominant or homozygous
recessive
 Heterozygous alleles
 hybrid
 Self fertilization