Download Reporting Category 2

Reporting
Category 2
MECHANISMS OF GENETICS
Part 1 – DNA components, Protein
Synthesis, Gene Expression, Meiosis &
Mutations
DNA
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Deoxyribonucleic Acid
Contains genetic information
Shape is a double helix
(twisted ladder)
Made up of nucleotides
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Sugar (Deoxyribose)
Phosphate
Nitrogen Base
DNA
There are 4 Nitrogen bases
 Adenine - A
 Guanine - G
 Cytosine - C
 Thymin - T
 Chargaff’s rule says
(Apple Tree Chewing Gum)
 A and T always pair
 G and C always pair
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DNA

COMPONENTS THAT MAKE UP THE
GENETIC CODE ARE COMMON TO ALL
ORGANISMS
PROTEIN SYNTHESIS
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TRANSCRIPTION
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TRANSLATION
TRANSCRIPTION
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Messenger RNA (mRNA) reads and copies the
DNA in the nucleus
DNA is too big to leave the nucleus
mRNA then leaves the nucleus to take the
information to the ribosome (in the
cytoplasam)
The DNA then winds back up
Which process is next?
TRANSCRIPTION
•Uses complementary nucleotides just like
replication
•Except that A pairs with U instead of T
TRANSLATION
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mRNA is taken to the ribosome to be translated
into protein (amino acids)
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tRNA brings the right amino acid to the
ribosome
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We translate using a sequence of three
nucleotides
 Called a codon
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We use a codon chart for translation
TRANSLATION
HOW DNA CREATES A TRAIT
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Each codon code for a
particular amino acid
Use the codon chart to
figure out the amino acid
USING A CODON CHART
MUTATIONS
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Any change in a nitrogen base
Mutations can create new traits
Not always BAD; some are beneficial 
think about mutations that lead to
adaptations!
Passed on through SEX CELLS (gametes)
Caused by a variety of things such as
CHROMOSOMAL MUTATIONS
POINT MUTATIONS
POINT MUTATIONS
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Remember that mutations can be silent
(unnoticed) if the amino acid is NOT
changed by the mutation!
MUTATIONS
GENE EXPRESSION
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Gene Expression is a regulated process
Proteins control the traits
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Genotype and Phenotype
DNA wound tight = gene off
DNA open = gene on
Meiosis
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Division of the sex cells
(gametes)
Makes 4 new haploid
cells
Haploid vs diploid
Crossing over increases
genetic diversity so cells
are NOT identical
Reporting
Category 2
MECHANISMS OF GENETICS
Part 2 – Genetic Crosses, DNA
Technology
PHENOTYPE
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Refers to what is
visible – either
the dominant or
recessive trait
How do you
know the
phenotype?
LOOK!!
GENOTYPE
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Refers to the
combination of alleles
Only 3 possibilities
 BB = Homozygous
Dominant
 Bb = Heterozygous
 bb = Homozygous
recessive
Must look at
inheritance pattern to
find out.
Punnett Squares
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Monohybrid (Bb x bb) – Crossing 1 trait
Dihybrid (BbSs x BBSS) – Crossing 2 traits
Parent, F1, F2 generations
Ratio Prediction—BbSs x BbSs???
MONOHYBRID
MONOHYBRID
PUNNETT SQUARE
•Homozygous Dominant
•YY
Y
y
Y
Y
Yy
•¼ or 25%
•Heterozygous
•Yy
Y
•2/4 or 50%
•Homozygous Recessive
•yy
•¼ or 25%
y
Yy
yy
DIHYBRID
DIHYBRID
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Remember to FOIL each parent separate
(Male)YyTt x (Female)yytt
MALE:
First = YT
Outer = Yt
Inner = yT
Last = yt
FEMALE:
First = yt
Outer = yt
Inner = yt
Last = yt
DIHYBRID
NON-MENDELIAN INHERITANCE
Incomplete Dominance
 red and white flowers

codominance
Black and white chickens
Sex Linkage
Females
are XX
Males are XY
Sex-linked traits are
on X chromosome
Trait is more
common in MALES
Examples are
colorblindness and
hemophilia (blood fails
to clot)
• Males give X chromosomes to
their daughters and Y’s to their
sons
• Moms give X’s to both
daughters and sons
PEDIGREES
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•
•
•
•
•
•
Tracing traits through
generations
Males are squares
Females are circles
Horizontal line means
married
Vertical line means
children
Filled in circle means the
individual HAS the
condition
Can you identify the
genotypes of individuals 4,
7, 12?
4 = Ee (parent 2 had to give an e)
7 = Ee (child is ee, so they had to have one e)
12 = ee (affected with recessive condition)
KARYOTYPES
In humans, 22 pair of
autosomes
1 pair of sex chromosomes
XX = female
XY = male
Extra chromosomes a result
of non-disjunction
•
•
•
•
•
•
•
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Chromosome pairs fail to separate in
meiosis
One example is DOWN SYNDROME
(extra 21)
Another example is KLINEFELTERS
(XXY)
3 21’s =
Down
Syndrome
XY = male
GENETIC TECHNOLOGY
TRANSGENIC
organisms
•Organisms
that have
2 different kinds of
DNA
•Gene cloning
•Uses bacteria to
make human proteins
like insulin
DNA
FINGERPRINTING
•Use
gel
electrophoresis
to compare DNA
fragments
•IF DNA
matches, it’s
from the same
individual
Evidence points
to suspect 2