Transcript Unit test review

Molecular Genetics
Thursday, March 16-12,
2010

Objectives
 State
that genes are codes for proteins.
 Identify the parts of a nucleotide.

Catalyst
 Widows
peak is dominant to straight
hairlines. Show the cross between two
heterozygous widow’s peak parents.
 Find the genotype and phenotype ratios.
Agenda
The Big Picture
 Quiz-Quiz-Trade
 Punnett Review
 Transcription/Transl
ation
 Independent Work
 Exit Question

In The Beginning…

Human beings have 23 pairs of chromosomes (one
 DNA is made up of two strands
from mommy, one from daddy).
 Each
of nucleotides in a double helix.
chromosome is made
 Nucleotide: backbone (sugar and
up of coiled DNA.
phosphate) plus a base.
 A specific area of
Genetic
information is stored in
chromosomethat
codes for
the anitrogenous
bases.
one trait is called
gene.

A
T
Chromosomes 
genes
G  C
 DNA
Controls a Trait? How?



Different alleles (versions) of genes code for
different traits.
We can predict what traits children will have if we
know their parents’ alleles.
A heterozygous free earlobe parent mates with a
heterozygous free earlobe parent.
How? Where?

OK, so genes code for traits—but how do we
get from a gene to a trait?
 Proteins!
Proteins are the stuff that actually
causes our hair to be blonde, eyes to be brown,
skin to be dark, etc.

Problem
 Chromosomes
(genes) are in the nucleus.
 Proteins are made in the ribosome.

OH NOES!!!
The Solution
X
X
X
X X
X
X
X
X
The Solution
CGATTA
GCUAAU
GCU = Alanine
AAU = Asparagine
TRANSLATION:
TRANSCRIPTION:
 Information in mRNA
read
DNA is iscopied
one
into codon
mRNA(three nucleotides)
a time.
 at
mRNA
is formed by
 tRNA
brings the base
correct
complementary
pairs
amino
acid,
on the
 A  U,
T based
A
codon
 G  sequence.
C, C  G
 Many amino acids = protein.
The Central Dogma of Biology
DNA
Transcription
RNA
Protein
Translation
Quiz-Quiz-Trade




Find a partner. Quiz them with your question on
your notecard. If they can’t get it right, coach them
(coaching is not telling them the answer!)
Then your partner quizzes you.
Once you have each successfully answered your
question, trade your notecards. Then raise your
hand.
High-five someone with a raised hand. BAM! You’re
now partners.
Punnett Square Practice


In lions, the allele for yellow eyes is dominant to the
gene for brown eyes.
Show a cross between a lion who is heterozygous
and one who is homozygous recessive. What are
the genotypic and phenotypic ratios?
Punnett Square Practice (whiteboard)


In lions, the allele for yellow eyes is dominant to the
gene for brown eyes.
Show a cross between a lion who is heterozygous
and one who is homozygous recessive. What are
the genotypic and phenotypic ratios?
Punnett Square Practice (whiteboard)


In lions, the allele for yellow eyes is dominant to the
gene for brown eyes.
Nala has yellow eyes and Simba has brown eyes.
Nala is heterozygous. What are the chances that
they will have children who are homozygous
dominant? Who have brown eyes?
Punnnett Square Practice (Whiteboard)


In lions, the allele for yellow eyes is dominant to the
gene for brown eyes.
Simba got his beautiful brown eyes from his parents
Mufasa and Sarabi. However, both his parents had
yellow eyes. Show that this is possible since both his
parents are heterozygous. What were the chances
that this was going to happen?
TRANSCRIPTION and TRANSLATION
SHOWDOWN
In each of these, you
have to take a segment
of DNA and turn it into
mRNA
Showdown…
AAGTACGTCATTCCGTAT
Showdown…
TACCATATTGGACAGAAA
Showdown…
TACGTTAATCAGAAATGT
Go over blood typing problem on
review sheet

Questions 40,41,42.
Independent Work Time
Exit Questions
What is ONE question you have
about this unit?
 I will review the most common
questions tomorrow before the
unit test.
