Genetics
Chapters 9 and 12
Introduction to Genetics
•
Genetics
is the science
of heredity and
variation in living
organisms.
•
Every living thing has
inherited
a set of
characteristics from its
parent or parents.
•
Traits
–
genetically
determined variant of a
characteristic
Francis Crick's first sketch of
the deoxyribonucleic acid
double
-
helix
•
At its most fundamental
level,
inheritance in
organisms occurs by
means of discrete traits
,
called “
genes
”.
•
This property was first
observed by
Gregor Mendel
Introduction to Genetics
http://en.wikipedia.org/wiki/Genetics
Chapter 12: Day One
Introduction to Genetics
The molecular basis for genes is:
deoxyribonucleic acid.
http://en.wikipedia.org/wiki/Genetics
Chapter 12: Day One
DNA
Good thing to know.
Gregor Mendel
•
Called the father of
genetics for his study of
the inheritance of traits
in pea plants.
Chapter 11: Day Five Start Here
http://en.wikipedia.org/wiki/Gregor_Mendel
Gregor Mendel
•
Used garden peas and
studied 7 specific traits
•
These different varieties
of peas are called
true
-
breeding
because
they
always pass on their
traits to their offspring
Chapter 11: Day Five
http://en.wikipedia.org/wiki/Gregor_Mendel
Gregor Mendel
•
Normally the flowers of
pea plants
self
-
pollinate:
the
pollen
(
male sex cells
)
and the
ovum
(
female sex
cells
) come from the
same flower
Chapter 11: Day Five
Gregor Mendel
•
He studied 7 specific
traits
•
Each trait had 2 possible
forms (
alleles
)
•
Allele
-
one of a number
of different forms of a
gene
P generation Cross
P generation
Original true
-
breeding
plants
F1 generation
Hybrid
plants
-
offspring that
have inherited 1 trait from
each parent
Chapter 11: Day Five
r
r
r
r
r
r
P generation Cross
•
Mendel concluded that
each P1 parent had
2
identical genes for each
trait
AND
that 1 allele
must be
DOMINANT
and the other
RECESSIVE
Chapter 11: Day Five
Why are the F2 hybrids
all red?
r
r
r
r
r
r
•
Genotype
-
the letter combinations showing
possible alleles
•
Identical alleles are
homozygous
•
Opposite alleles are
heterozygous
•
Phenotype
is the form of the trait that shows
up in what the organism looks like
rr = homozygous white
Rr = heterozygous red
RR = homozygous red
white
red
or
Chapter 11: Day Five
F1 generation
F2 generation
Chapter 11: Day Five
3:1 ratio
r
r
r
r
r
r
RR
rr
Rr
Rr
3:1 ratio, why is that?
When each F1 plant flowers and produces
gametes, the 2 alleles segregate from each
other so that each gamete carries only a
single copy of each gene.
Therefore, each F1 plant produces 2 types of
gametes
-
those with the allele for redness
and those with the allele for whiteness.
Mendel’s Results
& Conclusions
•
Law of Segregation
–
a pair of factors is
segregated, or separated, during the formation
of gametes
•
Law of Independent Assortment
-
factors
separate independently of one another during
the formation of gametes
Gregor Mendel Review
•
The inheritance of biological characteristics is
determined by individual units known as genes.
Genes are passed from parents to their offspring.
•
The principle of dominance states
-
some alleles
are dominant and some others are recessive.
•
During gamete formation, alleles segregate from
each other so that each gamete carries only a
single copy of each gene.
•
Principle of independent assortment
–
alleles
segregate independently
Inheritance Pattern
and Human Genetics
Chapter 12
Chromosomes
•
Sex chromosomes
–
Contain genes that determine the sex of an
individual
•
Autosomes
–
All the other chromosomes
This is old news.
Sex Determination
Sex
-
Linked Trait
•
A trait that is coded for an allele on a sex
chromosome
Most X
-
linked alleles have no counterpart on the Y chromosome.
Bigger, has
more
information
r
Is
something
missing
here?
Linked Genes
•
Pairs of genes that tend to be inherited
together, found on same chromosome
Dude, I
ain’t
going
nowher
e!!
Don’t
leave
me,
man!!
Chromosome Map
•
A diagram that shows the linear order of
genes on a chromosome.
Mutations
•
A change in the nucleotide
-
base sequence.
•
Involve an entire chromosome or a single
nucleotide.
Germ cell:
Occurs in the
organism’s
gametes.
Passed onto
offspring.
Somatic
-
cell:
Take place in
organism’s own
body cell
Lethal:
Cause death.
Chromosome Mutations
•
Deletion
–
Loss of a piece of chromosome
•
Inversion
–
Segment breaks off, flips, and reattaches
•
Translocation
–
Piece breaks off and reattaches to different chromosome
•
Nondisjunction
–
Chromosome fails to separate from its homologous
partner during meiosis
Gene Mutations
•
Point mutations
–
Change that occurs within a single gene or other DNA
segment
•
Substitution
–
One nucleotide replaces another
•
Frameshift mutation
–
Loss of nucleotides cause incorrect grouping of codons
•
Insertion mutation
–
One or more nucleotides are added to a gene, which can
also result in a frameshift mutation
See page 240
Pedigree
•
A diagram that shows how a trait is inherited
over several generations.
Genetic Traits and Disorders
•
Genetic disorders
–
Diseases or disabling conditions that have a
genetic basis
•
Complex characters
–
Characters that are influenced strongly by the
enviroment and by genes
Beyond Gregor Mendel
•
Some alleles are neither dominant nor
recessive, and many traits are controlled by
multiple alleles or multiple genes.
–
Incomplete dominance
–
Codominance
–
Multiple alleles
–
Polygenic traits
Polygenic
•
Characteristics are influenced by several genes
Multiple Alleles
•
Genes with 3 or more alleles
Codominance
•
Both alleles are expressed
Incomplete Dominance
•
A trait that is blended
Genetic Engineering
•
Genetic engineering, recombinant DNA
technology, genetic modification/manipulation
(GM) and gene splicing are terms that are
applied to the direct manipulation of an
organism's genes.
Chapter 13: Day Seven
http://en.wikipedia.org/wiki/Genetic_engineering
http://www.foxnews.com/images/330367/0_61_121207_cat.jpg
Cloned glow in the dark cats.
Genetic Engineering
There are a number of ways through which genetic
engineering is accomplished. Essentially, the process
has four main steps.
1) Isolation of the gene of interest
2) Insertion of the gene into a vector
3) Transformation of cells of organism to be modified
4) Tests to isolate genetically modified organism (GMO)
Chapter 13: Day Seven
http://en.wikipedia.org/wiki/Genetic_engineering
Lab Assignment
•
In your team, begin discussion on what you
think genetic engineering is and your position
on stem cell research.
Chapter 13: Day Seven Stop Here
AFP / Getty Images
Enter the password to open this PDF file:
File name:
-
File size:
-
Title:
-
Author:
-
Subject:
-
Keywords:
-
Creation Date:
-
Modification Date:
-
Creator:
-
PDF Producer:
-
PDF Version:
-
Page Count:
-
Preparing document for printing…
0%
Σχόλια 0
Συνδεθείτε για να κοινοποιήσετε σχόλιο