Download Notes Genetic Chapter 12 Complete

Gregor Mendel, Heredity and Genetics Notes
1. Heredity; the passing of traits from parents to offspring or young.
2. Genetic Traits or Inherited Traits; characteristics or features of an organism caused by genes.
A. hair color, eye color, number of toes
3. Acquired Traits: Traits that are earn, learned or gained during your life
knowledge, scares, abilities
4. Genetics; the study of heredity.
- The study of how our genes effect us and our offspring
- The Study of how to fix and treat genetic diseases
Genetic diseases; sickle cell anemia, cystic fibrosis, downs syndrom, hemophilia,
colorblindness, some cancers, sold sores
Gregor Mendel and his experiments
5. Lived in Europe in the late 1800's as a monk. Received degrees in mathematics and biology.
Because of his work he is know as the father of genetics.
6. Studied the heredity of pea plants. (His experiments are still famous today.)
1st step; crossed a tall plant with a short plant (both being purebred for that trait)
*purebred: tall always produce tall
P1
purebred tall + purebred short
TT
tt
F1
offspring all tall (hybrid)
Tt
2nd step; crossed or self pollinated the tall hybrid or
`F1
hybrid tall (Tt) + hybrid tall (Tt)
F2
(F1 generation) plants.
offspring tall and short plants
(3 tall plants to every 1 short plant)
Mendel’s results and conclusions
1. Factors that control traits are genes
2. Organisms inherit genes in pairs. One from each parent
- Different forms of the gene are called Alleles
3. Some alleles are dominant and some are recessive.
A. dominant trait: a trait that covers up another trait and shows itself.
B. recessive trait: a trait that is covered up by a dominant trait.
4. Genes are segregated during the formation of reproductive cells.
•
The garden pea plant is a good subject for studying heredity because:
– the plant has many contrasting traits,
– It is easily pollinated
– It grows fast and easily
– It produces many offspring
Important Genetic Terms
7. Allele: Different forms of a gene.
8. Genotype: the combination of genes for a specific trait
PP, pp (homozygous) the same genes or alleles
Pp (Heterozygous) different alleles or genes
9. Phenotype: the physical expression or appearance of a trait
Purple or White
General
Trait
Dominant
Allele
Recessive
Allele
Stem Length
Phenotype Genotype -
Seed Shape
Seed Color
Flower Color
Pod Color
Tall
TT
Phenotype Genotype -
Round
RR
Phenotype - Yellow
Genotype - YY
Phenotype - Purple
Genotype - PP
Phenotype Genotype -
Green
GG
Phenotype - Short
Genotype - tt
Phenotype Genotype -
Wrinkled
rr
Phenotype - Green
Genotype - yy
Phenotype - White
Genotype - pp
Phenotype Genotype -
Yellow
gg
Mutations and Genetic Rules
1. Mutation: and change in the genes or in the genetic material of the cell
Germ mutations: mutation in the germ cells (Cells that make sex cells)
- germ mutations are pass on to the next generation.
Somatic mutations: mutation in the normal body cell.
- somatic mutation are not passed on to the kids
2. Gene mutation: mutation in the gene.
Most mutations are gene mutation. (Spiderman had a gene mutation)
A point mutation is a mutation due to one change in the gene code.
3. Chromosomal mutation: mutation that effect the whole chromosome.
Non-Disjunction: Mutation where the homologous chromosome don’t separate
during meiosis
http://medgen.genetics.utah.edu/
- Down Syndrome: cause by getting 47 not 46 chromosomes, individuals get
3 of the 21st pair of chromosomes. (Trisomy 21)
- physically and mentally challenged
-Trisomy 13: Caused by having three #13 chromosomes
- extra finger or extra toes
- Cleft lip
- Turner Syndrome: (45X) caused by individual getting only one X sex
chromosome
- looks like girl but develops and can’t have children
- Klinefelter Syndrome: (47XXY) caused by individual getting 2 X and 1 Y
sex chromosome.
- Individual looks like boy, but they are sterile (can=t have children)
Mendel’s Rules and Modern Rules
1. Mendel Rule #1 Factors that control traits are genes.
- All Inherited trait come from a gene that makes a protein that helps build or
make the trait.
- Exception to the rule: Acquired traits are traits that organism get or
earn during their life times
2. Mendel Rule #2 Organisms inherit genes in pairs. One from each parent.
- Organism that reproduce sexually have two parents and inherit genes from a
male parent and a female parent.
- Exception to the rule: Some organism only reproduce asexually and
have only one parent.
- Bacteria reproduce asexually
3. Mendel Rule #3 Some genes (Alleles) are dominant and some are recessive.
- This rule is almost always true, but there are exceptions.
- Exception #1 Incomplete Dominance: inheritances pattern where neither
allele is dominant
Example - A dominant homogeneous red carnation (RR) crosses with a
with recessive homogenous white carnation (rr) and all the heterogeneous
offspring are Pink (Rr)
- Exception #2 Codominance: a condition where both alleles try to be dominant
and are expressed.
Example - In cows a homogeneous Red cow (RR) that is crossed with a
homogenous white cow (WW) and the offspring are roan (RW)
- Roan looks pinkish brown but it really is a mixture of red and white
hairs
- Sickle cell anemia: a genetic disease caused by a point mutation (a single
nucleotide change) making codominant alleles that cause red blood cells to be
bent and twisted making it hard for them to move through blood vessel, causing
pain and even death.
- Alleles; HA = normal cells allele, HS = sickle cell allele
-Genotypes HA HA = Normal red blood cells
HA HS = Half red blood cells are normal and half are sickle shaped
HS HS = suffer from sickle cell anemia
- Exception #3 Multiple alleles: traits that are controlled by 3 or more alleles.
Example - How tall people are is control by several thousand gene pairs.
- Skin color
- Human blood Type
- Blood types are classified by what kind of blood antigen it has
- Antigen: blood protein that causes antibodies to be made
- 4 main types of A, B, AB, O
- People with AB blood can receive any blood
- Blood type O can give blood to anybody
- Any antigen that is foreign to the body is attacked
- Rh factor: is another antigen in the blood. People with the Rh
factor positive and people who don=t are negative.
- people who have O blood would be either O+ or O
Mendel Rule #4 (Independent Assortment) Genes for different traits assort and
segregate independently of one another.
- True rule is chromosomes assort independently.
- All genes can’t assort independently because some genes are on the
same chromosome.
- These genes are said to be Gene Linked.
- see gene map on page 209
In fruit fly’s - black bodies are linked to small wings
- grey bodies are linked to normal wings
- Grey body and Normal wings are dominant
- so every grey body should always have normal wings
More Independent Assortment
- Crossing-over: Process where homologous chromosomes trade pieces of the
chromatids during meiosis.
- Sex-linked Genes: Genes that are one of the sex chromosome. Mostly the X
Examples
- Red and white eyes in fruit fly=s
- Color blindness
- People can’t see colors
- How do they pick tomatoes?
- What do they do at traffic lights?
- caused by a recessive allele on the X chromosome Xc
- Affects more men than women. Because men only need one color blind
allele (Xc Y) and women need two ( Xc Xc). Heterozygous women have
normal vision (XC Xc) Women with this genotype are called carrier
.
- Hemophilia (bleeders disease)
- Blood won=t clot and can=t stop bleeding
- caused by a recessive allele on the X chromosome Xh
- Affects more men than women. Because men only need one hemophilia
allele (XhY) and women need two ( Xh Xh).
- Heterozygous women have normal blood (XH Xh)
- Muscular Dystrophy: a genetic disease from a gene on the X chromosome
that results in the wasting away of skeletal muscle.
Baldness: a sex influenced trait that show up in men more than women
(BB) Normal hair
(Bb) Normal hair for women, baldness for men
(bb) bald for both men and women
Huntingtons: Disease caused by a mutated dominant allele (gene) found on the X
chromosomes that causes a person in their thirties or forties to get a nerve disease that
is fatal.