Transcript GENETICS

Bellwork 11/24
Balance the following equations:




Na
HgO

Make sure you write the
question and the full
answer. You need to work
out the problem
+
+
Br2
Cl2
NaBr
HgCl
+
O2
GENETICS
3.d. Describe heredity as the passage of instructions from one
generation to another and recognize that heredity information is
contained in genes, located in the chromosomes of each cell. (DOK 2)
How traits are passed from parents to offspring through pairs of genes
Phenotypes and genotypes
Hierarchy of DNA, genes, and chromosomes and their relationship to
phenotype
Punnett Square calculations
Vocabulary words for Genetics unit. The definitions
are in the book. We will have a vocabulary quiz
tomorrow.
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Heredity
Trait
Genetics
Fertilization
Purebred
Gene
Alleles
Dominant allele
Recessive allele
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17.
Hybrid
Probability
Punnett square
Phenotype
Genotype
Homozygous
Heterozygous
Codominance
Bellwork 11/25 – turn in when
finished & study for quiz
Which of these would happen to the cell if
cellular respiration stopped?
A. It would not have the energy it needs to
perform its functions.
B. It would grow larger because it would not be
able to dispose of wastes.
C. It would have to access backup energy
trapped in the chemical bonds of food.
D. It would no longer be able to passively
transport materials across its cell membrane.
Heredity

The passing of physical characteristics
from parents to offspring
Trait

A characteristic that an organism can
pass on to its offspring through its genes
Height
 Eye color
 Hair color

Genetics
The scientific study of heredity
 Discovered by Gregor Mendel


Experimented with pea plants
Fertilization

The process in which an egg cell and a
sperm cell join to form a new organism
Purebred

The offspring of many generations that
have the same trait
Purebred short pea plants always come
from short parent plants
 Purebred German Sheppard dogs always
come from German Sheppard parents


There will be no other species of that organism
in the blood line
Gene

Factors that control a trait
Alleles

Different forms of a gene
An organism’s traits are controlled by the
alleles it inherits from its parents.
 Some alleles are dominant, while other
alleles are recessive

Dominant allele

One whose trait always shows up in the
organism when the allele is present

Always represented by a capital letter
Recessive allele

One whose trait is hidden whenever the
dominant allele is present
A trait controlled by a recessive allele will
only how up if the organism does not have
the dominant allele
 Always represented by a lower case letter

Hybrid
Has two different alleles for a trait
 An organism that is heterozygous for a
particular trait

Codominance
The alleles are neither dominant nor
recessive
 As a result, both alleles are expressed in
the offspring

DNA
Deoxyribonucleic Acid
 Contains the biological instructions that
make each species unique
 Carry the genetic code
 Located in the nucleus of a cell
 Made up of genes which are located on
chromosomes

DNA
Made up of genes which are located on
chromosomes that are found in the
nucleus of a cell
 DNA carries the heredity material that
makes up your unique characteristics

Phenotype

An organism’s physical appearance or
visible traits
Blonde hair
 Brown eyes
 Tall
 Widows peak

Genotype

An organism’s genetic makeup or allele
combinations
GG
 Gg
 gg
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Homozygous

An organism that has two identical
alleles for a trait
SS
 ss
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Heterozygous

An organism that has two different
alleles for a trait

Rr

Mendel used the term hybrid to describe
heterozygous organisms
Probability

A number that describes how likely it is
that an event will occur
Punnett Square

Is a chart that shows all the possible
combinations of alleles that can result
from a genetic cross

In a genetic cross, the allele that each
parent will pass on to its offspring is based
on probability
Filling out Punnett Squares
1.
Start by drawing a box and dividing it
into 4 squares
Filling out Punnett Squares
2.
Write the male parent’s alleles along
the top of the square and the female
parent’s alleles along the left side
Filling out a Punnett Square
3.
Copy the female parent’s alleles into
the boxes to their right and the male
parent’s alleles into the boxes beneath
them
Filling out a Punnett Square
4.
The completed Punnett square shows
all the possible allele combinations in
the offspring
Examples

A pea plant with round seeds has a
genotype of Rr. You cross this plant with
a wrinkled seed plant, genotype rr. What
is the probability that the offspring will
have wrinkled seeds?
Examples

In guinea pigs, the allele for black fur (B)
is dominant over the allele for white fur
(b). In a cross between a heterozygous
black guinea pig (Bb) and homozygous
while guinea pig (bb), what is the
probability that an offspring will have
white fur?
Examples

In rabbits, the allele for a spotted coat is
dominant over the allele for a solidcolored coat. A spotted rabbit was
crossed with a solid-colored rabbit. The
offspring all had spotted coats. What are
the probable genotypes of the parents?
Explain.
Examples

A long haired rabbit (Bb) is crossed with
a short haired rabbit (bb). Using a
Punnett square, what is the probability
for all phenotypes and gentotypes?