Transcript PARENT #2

Objective: Students will be able to complete a
gallery walk activity in order to review for the
Genetics Unit of the Biology HSA exam.
Drill:
1. Take out the cards your teacher has given you.
2. Match up the vocabulary words with the definition and the picture
that best represents each word.
3. Work with your neighbor to discuss answers and then copy the
correct answers onto your “Genetics Vocabulary Chart.”
Objective: Students will be able to complete a
review in order to prepare for the Genetics Unit of
the Biology HSA exam.
Drill:
1. If you see Natural selection in a test question, what should you
do?
2. If you just don’t know the answer, what should you do?
3. Should you always read the questions and all of the answers
before making your choice?
Vocabulary
Genotype
Phenotype
Homozygous
Definition
The alleles (letters) that
represent a trait. TT or tt
The external or
physical appearance of
a gene. black
Both alleles (letters) for
gene are same
Alleles (letters) for the
gene are different
Heterozygous
Picture
Think-Pair-Share: work with your neighbor and
complete questions #1-4 on your “Punnett Square
Practice Problems” worksheet.
Let’s review the answers as a class, then try some more
Punnett squares.
A “Punnett square” is an easy tool that is used to
determine the traits that are passed on from parent to
offspring.
The first step is to draw a naked Punnett square, which
looks like a window pane.
Step two: place the alleles for the parents’ traits on the
outside of the Punnett square.
W
W
Mom has purple
flowers: WW
Dad has white
flowers: ww
w
w
The squares inside the Punnett square represent the
traits of the children the couple would have.
Step three: Drop each of
the top alleles down in a
box below it.
Step four: Carry each
allele on the side over
to each box
W
Ww
W
Ww
w
Important: Always write
Ww
Ww
the dominant allele
before the recessive
w
allele
These letters represent the alleles each child received
from the parents.
The first generation of
offspring are called the F1
generation.
Since W is dominant it
covers up the recessive
w.
In this case all of the
offspring came out Ww,
so they will be purple.
W
W
Ww
Ww
Ww
Ww
w
w
Let’s complete #5-7 on your “Punnett Square Practice
Problems” worksheet.
Parent 1 Genotype:
b
Bb
Brown Fur
Parent 1 Phenotype:
B
Parent 2 Genotype:
b
Bb
Bb
bb
bb
bb
Parent 2 Phenotype: White Fur
b
Genotype ratio: 2 : 2
Phenotype ratio: 2 : 2
Roger has short ears. Genevieve is heterozygous for
long ears. Use the steps below to solve the problem.
Determine the parent’s genotype and phenotype
PARENT #1:
PARENT #2:
E
1. What are the chances of a baby
with the genotype Ee?
out of
or
%
e
2. What are the chances of a baby
with short ears?
out of
or
%
e
e
Ee
ee
Ee
ee
Complete the notes on
your “Chromosomes
and Sex-Linked Traits”
worksheet.
If we take all the
chromosomes out of one cell
and match them up, we find
that we have 23 pairs.
The first 22 pairs contain the
genes that make up our
bodies (called autosomes).
The 23rd pair are called sex
chromosomes because they
determine your gender.
XX
There are two different sex
chromosomes, X and Y.
If you receive an X and a Y, you
are genetically a male.
If you receive two X’s then you
are genetically a female.
XY
X chromosomes can carry other
traits besides those related to
gender.
Sex-Linked Traits
Hemophilia
Male Pattern Baldness
Red-Green Colorblindness
Duchenne Muscular Dystrophy
Today we will look at hemophilia.
In order to have offspring
you need a female XX
and a male XY.
These crosses work just
like the ones we have
done in the past.
XX= female baby
XY= male baby
Ratio = 2:2 or 50%
Since sex linked traits involve
sex chromosomes, we have to
use the letters X and Y.
We use superscript letters to
represent the trait. Since
hemophilia is recessive, we
will use a lower case “h”.
Now let’s try a cross involving
hemophilia to see how it works.
Hemophilia occurs when
people lack a protein that helps
clot blood.
X
Y
h
Remember in sex
linked traits the
allele is only on the
X chromosome!
Let’s cross a male with hemophilia with a carrier female.
XH
Xh
Genotype Phenotype
h
H
H
X
X X
Normal
h h
XHXh
XHXh
X x
XhXh
Carrier
hemophilia
XHY
Normal
XhY
hemophilia
XHY
Xh Y
Y
Since females have two X’s they need two alleles to get hemophilia.
Because males only have one X, they only need one allele to get
hemophilia.
Antoinette has
hemophilia but her
husband Bobby is
normal.
•Draw a Punnett
square to predict the
genotypes of their
children.
Xh
XH
Xh
XHxh
XHxh
XhY
XhY
•Determine how many
children will have
hemophilia.
Y
Interphase
Prophase
Metaphase
Anaphase
Telophase &
Cytokinesis
Two new
identical
cells
Mitosis starts
with one
parent cell.
Each daughter
cell also has 4
chromosomes.
Parent cell
starts with 4
chromosomes
Afterwards you
have two cells that
are identical to the
original cell.
Growth
Healing wounds
Asexual Reproduction in
Bacteria
Cancer
Sperm and Egg
are called
gametes and
only have a
haploid number
or 23
chromosomes.
Sperm and egg
are made by a
process of cell
division called
Meiosis.
46 chromosomes
Woman
produces
an egg.
23 chromosomes
The male
produces
sperm.
23 chromosomes
The sperm fertilizes the
egg to make a zygote.
Sperm and Egg only have 23 chromosomes and are created by a
process called meiosis.
The original
parent cell has 4
chromosomes.
Cell divides once.
Daughter cells
only have half
the number of
chromosomes.
Cells
then
divide
again
4 Sperm
1 Egg
Spermatogenesis
Oogenesis
Meiosis
Mitosis
Work with a partner to complete “Comparing and
Contrasting Mitosis vs. Meiosis” worksheet.
What information can we
learn from this pedigree?
Male
Female
4 Generations
Trait Inherited
What kind of trait is inherited in this family? How do you
know?
KEY
1
Normal female
2
Affected female
Carrier female
3
4
Normal male
Affected male
5
Sex-linked Trait
Genotypes:
1. ____
2. _____
3. _____
4. _____
5. ____
Transcription
Translation
Scribes were people that used to copy books before the
invention of the printing press.
Transcription- is when DNA is copied into RNA
DNA is our only copy of our genetic blueprint, so we
need to keep it nice and safe in the nucleus.
DNA has two
strands
DNA stays in
nucleus
DNA is larger
RNA only has one strand
RNA can go anywhere in
the cell
RNA is smaller
RNA has A,U, G, C.
DNA has A,T,G,C
We can make a copy of a portion of our DNA, called
RNA. We can then take RNA to our job site to build
our proteins. This RNA is called mRNA because it has
a message in it.
We learned earlier that DNA has a code that provides
instructions on how to build proteins. These
instructions are passed on to the mRNA
I’m a ribosome,
I read the code
in mRNA 3
letters at a time.
The code in mRNA is read 3 letters at a time. Every 3
letters is called a codon, which codes for an amino acid.
This step is called Translation.
Codon = three letters = amino acid
Third letter
GTA
CAG
We can now translate the mRNA. Each codon equals
an amino acid. We will get practice with pedigrees and
protein synthesis during our gallery walk next!
The artist captured
man’s inner struggle
with nature.
Yeah whatever. It
looks like a hot
mess to me!
You will work in groups of three to complete a gallery
walk on Genetics Review problems. You will have a set
time at each station.
Let’ review answers as a class.
We will do the first problem on the “What type of cross
am I” worksheet to model how it is done.
Your homework is to complete the other two problems.
Next class we will study for the evolution part of the HSA