Post on 15-Mar-2020
Biology Chapter 14
Interest Grabber A Family Tree
| NOTEBOOK #1
| To understand how traits are passed on from generation to generation, a pedigree, or a diagram that shows the relationships within a family, is used. In a pedigree, a circle represents a female, and a square represents a male. A filled-in circle or square shows that the individual has the trait being studied. The horizontal line that connects a circle and a square represents a marriage. The vertical line(s) and brackets below that line show the child(ren) of that couple.
Interest Grabber cont. | 1. This pedigree shows the inheritance of
attached ear lobes. Which parent has attached ear lobes?
| 2. How many children do the parents have? Which child has attached ear lobes?
| 3. Which child is married? Does this child’s spouse have attached ear lobes? Do any of this child’s children have attached ear lobes?
Autosomal Disorders
caused by
include include include
Autosomol Disorders
Recessive alleles
Dominant alleles
Codominant alleles
Albinism Galactosemia Tay-Sachs disease
Huntington’s disease
Sickle cell disease
Cystic fibrosis
Phenylketonuria Achondroplasia Hypercholes- terolemia
Pedigree
A circle represents a female.
A square represents a male.
A horizontal line connecting a male and female represents a marriage.
A vertical line and a bracket connect the parents to their children. A half-shaded
circle or square indicates that a person is a carrier of the trait. A completely
shaded circle or square indicates that a person expresses the trait.
A circle or square that is not shaded indicates that a person neither expresses the trait nor is a carrier of the trait.
Pedigree of Queen Victoria
Blood Groups
Phenotype (Blood Type) Genotype
Antigen on Red Blood Cell
Safe Transfusions To From
ABO Blood Type Multiple Alleles
| Type A: AA, AO
| Type B: BB, BO
| Type AB: AB
| Type O: OO
Blood Type Frequency
NOTEBOOK #2
1. What is a pedigree? 2. In a pedigree, females are
represented by what? Males? 3. In a pedigree, how is a carrier
represented? 4. What are the four blood types? 5. List the blood types in order from
most common to least common.
Interest Grabber- Notebook#3
Gender Benders | You may remember that in humans,
the sperm cells may carry an X chromosome or a Y chromosome, while egg cells have only X chromosomes. Sometimes, errors during meiosis in one of the parents produce offspring with an abnormal number of sex chromosomes.
Interest Grabber cont. | 1. On a sheet of paper, construct a Punnett
square for the following cross: XX x XY. Fill in the Punnett square. What does the Punnett square represent? According to the Punnett square, what percentage of the offspring from this genetic cross will be males? What percentage will be females?
| 2. On a sheet of paper, construct a Punnett square for the following cross: XXX x XY. Fill in the Punnett square. How is this Punnett square different from the first one you constructed? What might have caused this difference?
| 3. How do the offspring in the two Punnett squares differ?
Interest Grabber
X
X X
X
X X X
Y
Y
Nondisjunction
Homologous chromosomes fail to separate
Meiosis I: Nondisjunction
Meiosis II
Nondisjunction (Trisomy)
| Nondisjunction- failure of chromosomes to separate during cell division. Results in extra chromosomes in body cells.
Down’s Syndrome (Nondisjunction) Karyotype
Solving Sex-linked Problems
| The gene for hemophilia is found on the X chromosome
| Sex-linked traits are also called X-linked traits
| Hemophilia is a blood disease that does not allow the blood to clot
Colorblindness (sex-linked)- gene for the disease is carried on the X chromosome
Father (normal vision)
Colorblind Normal vision
Mother (carrier)
Daughter (normal vision)
Son (normal vision)
Daughter (carrier)
Son (colorblind)
Male
Female
Red-Green Colorblindness | Sex-linked
disease caused by the recessive gene
| Female | Normal: XCXC
| Carrier: XCXc
| Red-Green: XcXc
| Male | Normal: XCY
| Red-Green: XcY http://colorvisiontesting.com/ishihara.htm
Crossing Over | Crossing Over-
part of a chromatid on one homolog may break and rejoin with one of the chromatids belonging to the second homolog
Notebook #4
1. What is nondisjunction? What does it cause?
2. What is a sex-linked trait? Give an example.
3. How are sex-linked traits passed on?
4. Explain crossing over.
Duplication A duplication occurs when part of a chromosome is copied (duplicated) abnormally, resulting in extra genetic material from the duplicated segment
Translocation Translocation is a chromosomal disorder in which a fragment of a CHROMOSOME breaks from its original chromosome and attaches itself to a different chromosome.
Deletion A deletion occurs when a chromosome breaks and some genetic material is lost.
Insertion In this example, one nucleotide (adenine) is added in the DNA code, changing the amino acid sequence that follows
Inversion Inversions occur when a chromosome breaks in two places and the resulting piece of DNA is reversed and re-inserted into the chromosome.
Notebook #5
1. What is duplication? 2. What is translocation? 3. What is a deletion? 4. What is an insertion? 5. What is an inversion?
Interest Grabber – Notebook #6
Analyzing Inheritance | Offspring resemble their parents. Offspring
inherit genes for characteristics from their parents. To learn about inheritance, scientists have experimented with breeding various plants and animals.
| In each experiment shown in the table on the next slide, two pea plants with different characteristics were bred. Then, the offspring produced were bred to produce a second generation of offspring. Consider the data and answer the questions that follow.
Interest Grabber
| 1. In the first generation of each experiment, how do the characteristics of the offspring compare to the parents’ characteristics?
| 2. How do the characteristics of the second generation compare to the characteristics of the first generation?
Parents
Long stems × short stems
Red flowers × white flowers
Green pods × yellow pods
Round seeds × wrinkled seeds
Yellow seeds × green seeds
First Generation
All long
All red
All green
All round
All yellow
Second Generation
787 long: 277 short
705 red: 224 white
428 green: 152 yellow
5474 round: 1850 wrinkled
6022 yellow: 2001 green
Gregor Mendel | Austrian Monk who
studied the genetics of pea plants
| His work was not recognized until 1900, several years after his death
| Because of his work he is known as the Father of Genetics
Mendel’s Experiment
Principles of Dominance P Generation F1 Generation F2 Generation
Tall Short Tall Tall Tall Tall Tall Short
Genetic Terms | Dominant- prevents the expression of the recessive
genes { Represented by capital letters T
| Recessive- masked by the dominant trait { Represented by a lower case letter t
| Homozygous- two genes that are the same: TT, tt
| Heterozygous- two genes that are different: Tt
| Genotype- actual genes of an organism: TT, Tt, tt
| Phenotype- physical appearance of an organism: Tall, Short
| Probability- the likelihood that an event will occur: 50:50 chance of getting heads or tails
Mendel’s Seven F1 Crosses
on Pea Plants Seed
Shape Flower Position
Seed Coat Color
Seed Color
Pod Color
Plant Height
Pod Shape
Round
Wrinkled
Round
Yellow
Green
Gray
White
Smooth
Constricted
Green
Yellow
Axial
Terminal
Tall
Short
Yellow Gray Smooth Green Axial Tall
Punnett Square Complete Dominance
| Genotype: | 4Gg
| Phenotype: | 4 green
Tt X Tt Cross
Genotype: 1 TT : 2Tt : 1tt Phenotype: 3 Tall : 1 short
Punnett Squares – Notebook #7
Create Punnett Squares with the following crosses. Be sure to give the Genotypic and Phenotypic ratios. 1. SEED SHAPE: HOMOZYGOUS ROUND X HETEROZYGOUS ROUND 2. POD COLOR: HETEROZYGOUS GREEN X HOMOZYGOUS YELLOW 3. FLOWER COLOR: HETEROZYGOUS PURPLE X HETEROZYGOUS PURPLE 4. SEED COLOR: HOMOZYGOUS YELLOW X HOMOZYGOUS YELLOW
Notebook #8
1. Who is Gregor Mendel? 2. What is the difference between the
P, F1, and F2 generations? 3. What is the difference between
dominant and recessive? 4. What is the difference between
homozygous and heterozygous? 5. What is the difference between
genotype and phenotype?
Interest Grabber Height in Humans
| Height in pea plants is controlled by one of two alleles; the allele for a tall plant is the dominant allele, while the allele for a short plant is the recessive one. What about people? Are the factors that determine height more complicated in humans?
Interest Grabber cont. | 1. Make a list of 10 adults whom you
know. Next to the name of each adult, write his or her approximate height in feet and inches.
| 2. What can you observe about the heights of the ten people?
| 3. Do you think height in humans is controlled by 2 alleles, as it is in pea plants? Explain your answer.
Interest Grabber – Notebook #9
Tossing Coins | If you toss a coin, what is the probability
of getting heads? Tails? If you toss a coin 10 times, how many heads and how many tails would you expect to get? Working with a partner, have one person toss a coin ten times while the other person tallies the results on a sheet of paper. Then, switch tasks to produce a separate tally of the second set of 10 tosses.
1. Assuming that you expect 5 heads and 5 tails in 10 tosses, how do the results of your tosses compare? How about the results of your partner’s tosses? How close was each set of results to what was expected?
2. Add your results to those of your partner to produce a total of 20 tosses. Assuming that you expect 10 heads and 10 tails in 20 tosses, how close are these results to what was expected?
3. If you compiled the results for the whole class, what results would you expect?
4. How do the expected results differ from the observed results?
Interest Grabber continued
Concept Map
concluded that
which is called the
which is called the
Gregor Mendel
Law of Dominance
Law of Segregation
Pea plants
“Factors” determine traits
Some alleles are dominant, and some alleles are recessive
Alleles are separated during gamete formation
experimented with
Independent Assortment in Peas
The principle of independent assortment states that genes for different traits can segregate independently during the formation of gametes. Independent assortment helps account for the many genetic variations observed in plants, animals and other organisms.
Incomplete Dominance in Four O’Clock Flowers
Genotype: 4 RW Phenotype: 4 Pink
Incomplete dominance occurs when one allele is not completely dominant over another. They both contribute to the phenotype equally.
Codominance Blood type is a codominant trait, meaning that each allele fully expresses itself. In other words, neither allele dominates the other and each allele is equally emphasized.
RR = red cow hairs RW = red and white cow hairs WW = white cow hairs
BB = black feathers BW = black and white feathers WW = white feathers
Notebook #10 1. What is the principle of independent
assortment and when does it occur?
2. What is incomplete dominance?
3. What is codominance?
4. Compare and contrast incomplete dominance and codominance.