Download AIR Genetics Review PPT

Replication
• DNA will duplicate itself by separating the two
strands and pairing new bases to the old
strands
• This process is called semi-conservative
because the new DNA is made of one strand
that was “old” and one new strand
Protein Synthesis
1. Transcription
–
–
–
DNA unwinds
mRNA base pairs with
DNA
mRNA moves out of
nucleus
2. Translation
– Ribosome attaches to
mRNA
– tRNA, that contains an
amino acid (anticodon),
base pairs with mRNA
strand (codon). Amino
acids are linked together.
– Stop codon reached and
amino acid sequence is
released to fold (protein)
Mutations
• During either of these processes, the copying
of the DNA can result in mistakes (mutations)
Types of Mutations
• Point – one base is changed
• Substitution – one letter replaces another
• Insertion – one letter is added
• Deletion – one letter is removed
Biotechnology
• Genes can be manipulated through several
techniques:
– PCR: one copy of DNA is made into many copies
– DNA can be cut using restriction enzymes and
inserted into a new cell
– Gel Electrophoresis: cutting DNA with restriction
enzymes and separating the DNA based on size
– Cloning: using DNA from an organism and
inserting it into a new cell and promoting growth
Punnett Squares
• Dihybrid Crosses: two traits are examined and
how they are passed to offspring
• Steps (for unlinked traits):
– Write the cross
– Write all possible gamete combinations
– Use gamete combinations to create Punnett
square
In horses, black is dependent upon a dominant gene, B, and
chestnut upon its recessive allele, b. The trotting gait is due to a
dominant gene, T, the pacing gait to its recessive allele, t. If a
heterozygous black pacer is mated to a chestnut trotter
(heterozygous), what will be the appearance of the F1
generation?
Linked Traits
• Some dihybrid crosses will have traits that are
linked, meaning the alleles do not separate
from each other.
• For Example: If someone has the genotype
BbTt and the traits are linked, instead of
having four gamete combinations, now there
are only two: BT, and bt
Let's say Mr. and Mrs. Smiley both have the
genotype EeTt. That means they are both
hybrids, BUT the dominant alleles are linked.
What are the possible outcomes for offspring?
Punnett Squares
• Sex-Linked Traits: show how a trait is passed
on that is linked to an X or Y chromosome
• Steps:
– Show cross using XX for females, XY for males
– Use exponents for the particular trait
– Create Punnett square to see outcomes
Hemophilia is a recessive sex-linked disease carried on the X
chromosome in humans. A woman who is a carrier for
hemophilia marries a man with hemophilia. Could any of their
children have hemophilia? If so, would the child be male or
female?
Punnett Squares
• Co-dominance: When the heterozygous
individual has a both the dominant and
recessive trait
– Example: A white and red spotted flower
• Incomplete Dominance: When the
heterozygous individual has a blending of the
dominant and recessive trait
– Example: A pink flower
A pink-flowered plant is crossed with a whiteflowered plant. What is the probability of
producing a pink-flowered plant?
In some chickens, the gene for feather color is controlled by codominance. The allele for black is B and the allele for white is W.
The heterozygous phenotype is known as erminette. A black
chicken and a white chicken are crossed. What is the probability
that they will have erminette chicks?
Pedigrees
• A pedigree is a diagram of family relationships
that uses symbols to represent people and
lines to represent genetic relationships
• A pedigree can also help determine how a
trait is passed on through generations
What are the genotypes of the
individuals if this pedigree is showing
how tongue rolling (a recessive trait)
was passed through a family?
Chi-Square