Transcript Genetics

Genetics
A: describe how Mendel developed his
theories of genetics;
☻ Gregor Mendel (1822-1884)
☻Austrian Monk
☻First person who developed a workable model of
genetics.
☻Educated man who studied sciences and math.
☻1.) Pea plant is ideal: Long and short
stems, round and wrinkled seeds.
☻Complete flower (male and female parts
on one flower)
☻Flower enclosed by petals prevents
crossbreeding
☻2.) First developed purebred strains
☻Characteristics would carry through to the
next generation.
☻Tall plant would always produce a tall
plant.
☻3.) Next cross purebred lines of plants by
removing the male flower parts and cross
pollinating.
☻They are called the F1 generation
☻The new plants had all red flowers leading
to the law of dominance.
☻4.) Then crossed F1 generation; these
seeds are now the F2 generation.
☻This generation, white flowers again
showed up.
☻Altogether found same results with seven
traits of pea plants.
B: Explain the Mendelian laws of genetics;
☻Law of Dominance: certain traits are
dominant and make recessive traits
appear to disappear.
☻Later scientists called these dominant or
recessive traits allels.
C: Define vocabulary terms of heredity;
☻Chromosomes- rod shaped bodies that
occur in pairs in the nuclei of the cell and
that carry the genetic makeup.
☻Genetics- study of how traits are passed
from one generation to another.
☻Genes- heredity units located on a
chromosomes.
☻DNA- ( Deoxyribonucleic acid) a nucleic acid
that makes up chromosomes and controls
inherited traits.
☻Allele- place on a gene that results in a
dominant or recessive trait.
☻Homozygous- pertaining to the condition in
which both genes at a particular location are the
same allele or are identical (either dominant or
recessive)
☻Heterozygous- pertaining to the
conditions in which two alleles are given
location.
☻Dominant- expressive gene, these are
indicated by capital letters.
☻Recessive- the genes do not express
themselves; these are represented by
lowercase letters.
☻Probability- the likelihood that some events or
outcome will occur.
☻Meiosis- cell division that produces gametes,
which contain the haploid number of the
chromosome.
☻Phenotype- how an allele expresses itself.
☻Genotype- the genetic composition of an
individual.
☻Law of Independent Assortment:
factors (genes) for certain characteristics
are passed from parents to the next
generation separate from the other factors
or genes that transmit other traits.
☻Gene for a tall pea plant does not effect
color at all.
D: compare and contrast phenotype and
genotypes;
☻Phenotype- how an allele expresses itself.
☻What it looks like
-can see it
☻Controlled by genotype - dominant gene is seen
☻Genotype- the genetic composition of an
individual.
☻Cannot see it (Rr)
☻Traits
-Expressed in phenotype
- dominant seen
☻50% from each parent - only 5% different from all
other humans
E: Analyze Punnett squares;
☻R.C. Punnett mathematician developed a
diagram to illustrate possible combinations for a
trait.
☻Letters are used to illustrate traits. Capital letter
indicates dominant trait. Lower case letter
indicates a recessive trait.
☻Alleles are paired for traits. They may be paired
in a homozygous or heterozygous matter.
F: Discuss the make up of chromosomes in a
cell;
All of the material responsible for the
transfer of traits is grouped together in
structures called chromosomes.
Rod shaped, X during Mitosis
Chromosomes are long strands of protein
and nucleic acid molecules. (DNA)
Can be arranged in an infinite number of
ways.
Within these molecules is the genetic
code that determines all the characteristics
of an organism.
Different segments of the chromosomes
control different traits that are expressed in
the organism.
Each chromosome segment that
controls a trait is called a gene.
Each cell of an organism contains all of
the DNA needed to control all traits of the
organism.
This makes cloning using a single cell
possible.
Genes
• Each gene on the chromosome has two
alleles
• One contributed by each parent.
• Off spring receives exactly half of their
genetic material from each parent.
At fertilization, the two cells, each
containing half the genetic code from each
parent, unite.
They form a new genetic code for the
fertilized egg.
There are huge numbers of ways that
genes can be paired.
Meiosis
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•
Meiosis is the process by which
reproductive cells are made.
The chromosomes divide in half to form
the gametes (sex cells).
They recombine when fertilization takes
place to insure that the new organism has
the correct number of chromosomes.
Who controls gender in off spring?
Male- x y
Female- x x
Parent cells
Gametes
Fertilization Occurs
Possible outcomes
G: Determine the structure and function
of DNA;
DNA
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•
Made of 2 strands that wrap around each
other. (Double Helix)
The building blocks: nitrogen bases:
Adenine (A)
Purines
Guanine (G)
Thymine (T)
Pyrimidines
Cytosine (C)
A-T always pair
G-C always pair
DNA is the genetic makeup/code or
blueprint for life.
H: Discuss the process of DNA replication and
transfer;
Prior to cell division the DNA copies itself in
a process called replication. (Interphase)
The strands of DNA separate,
Each half duplicates the missing side.
Now there are two strands exactly alike
Replication uses the following steps:
—
—
—
Separation of Standards
Base Pairing
Bonding of Base
RNA
The DNA’s message is transferred to the
rest of the cell by means of a messenger
known as RNA.
As the organism grows, the cells know
how to differentiate to form different parts.
K: Explain how hybrid plant varieties are
developed.
Hybrid plants take on superior
characteristics to the parent plant
known as hybrid vigor.
Parent plants must be purebred
(have the ability to breed true.)
Farmers can get larger yields,
tapered to their soil type, earlier in the
season.
Drought tolerance.
Heat resistance
Insect resistance
Disease resistance
Plants are able to cross-pollinate,
so scientists must ensure that
only the desired cross can occur.
It takes several generations
before the cross is complete and
ready to be grown in production.
First, purebred lines must be
developed, then they can be
crossed.
The parent line must be grown
for several generations to
prove that it will grow true.
They use the genetics
characteristics in a parent plant to
develop new cultivars that will out
perform their parents.
Plant breeders learned that
crossing two purebred lines
resulted in a more vigorous plant
known as a hybrid.
Different species of plants are known
as cultivars.
Plant breeders use genetic
characteristics of plants to breed new
cultivars that will grow in a specific
condition.
Plant breeders always have a definite
goal in what they are breeding for.
J: Specify how genetic principals are used in
plant breeding;
Plant breeding is the process of
matching genetic factors from parent
plants to produce offspring superior to
the parent plants.
Plant breeding has occurred for
hundreds of years. All plants now
grown were once wild.
Essay example answer:
DNA replicates during Interphase in the cell cycle.
First, the DNA splits by breaking apart at the
hydrogen bonds.
Next, the bases re-pair. A only pairs with T, and
C only pairs with G. this makes the pairing
possible.
Finally, the bases re-bond. That process of
replication produces 2 identical sets of DNA.
Now the cell is ready to divide in Mitosis.