CHAPTER 13 OBJECTIVES
After reading this chapter and attending lecture, the student should be able to:
1. Explain why organisms only reproduce their own kind, and why offspring more closely
resemble their parents than unrelated individuals of the same species.
Organisms produce their own kind as a consequence of heredity, offsprings resemble their parents because of their genes.
3. Distinguish between asexual and sexual reproduction.
Asexual is reproduction from one parent and sexual takes two parents to rproduce.
4. Diagram the human life cycle and indicate where in the human body that mitosis and
meiosis occur; which cells are the result of meiosis and mitosis; and which cells are haploid.
Meiosis occurs with the cell & egg cells. Meiosis alternates w/ fertilization.
Sperm/egg cells are produced by meiosis and somatic cell by mitosis
Haploids-cells contain one set of chromosomes
5. Distinguish among the life cycle patterns of animals, fungi, and plants.
In animals- gametes are the only haploid cells. In fungi-the only diploid stage is the zygote. In plants-alternation between multicellular haploids and diploid generations.
6. List the phases of meiosis I and meiosis II and describe the events characteristic of each phase.
Meiosis I - prophase I -chromosome condenses and synapsis occurs, and chromosomes detach from n.envelope. metaphase I -tetrads line up @ metaplate. Anaphase I -homologous separate , moving to opp. Poles. Telophase I -spindleaparatus continues to separate homologous chromosome piars until reach poles. (cytokinesis separates into 2 cells). Meiosis II - prophase Iispindle apparatus forms . Metaphase II - chromosomes are lined at metaphase plate. Anaphase II - sister chromatids seperateand move to opp. Lpoles. Telophase II - nuclei form at opp.f poles . ( cytokinesis produces 4 haploid cells)
7. Recognize the phases of meiosis from diagrams or micrographs.
know
9. Describe the process of synapsis during prophase I, and explain how genetic
recombination occurs.
Synapsis is the crossing over between two chromatids from the 2 chromosomes that form a tetrad. The genetic recombinations occur as the genes transfer fromone chromosome to the other.
10. Describe key differences between mitosis and meiosis; explain how the end result of meiosis differs from that of mitosis.
The mian differences are : synapsis , the lining up of tetrads (meiosis) and chromosomes(mitosis), and the seperation of chromosomes(meiosis) and chromatids (mitosis). The end results are mitosis+2 duaghter cells and meiosis+ 4 duaghter cells
11. Explain how independent assortment, crossing over, and random fertilization contribute to genetic variation in sexually reproducing organisms.
Independent ass. - random distribution of genes located in different chromosomes. Crossing over - homologous chromosomes exchange genes. Random fertilization - 1 of 8,000,000possible chromosomes combination is fertilized.
CHAPTER 14 OBJECTIVES
After reading this chapter and attending lecture, the student should be able to:
5. State, in their own words, Mendel's law of segregation.
The two alleles for a character are packaged into separate gametes.
6. Use a Punnett square to predict the results of a monohybrid cross and state the phenotypic and genotypic ratios of the F2 generation.
got it
7. Distinguish between genotype and phenotype; heterozygous and homozygous; dominant and recessive.
Homozygous- having 2 identical allelsfor a given trait . Heterozygous - having 2 different alleles for a trait. Phenotype- an organisms expressed traits. Genotype - an organisms genetic makeup. Dominant - having more of . recessive having less of.
8. Explain how a testcross can be used to determine if a dominant phenotype is homozygous or heterozygous.
for ex: if a purple flower plant of unknown genitype(P_) produced by only purple flowered plants the parent was most probably homozygous dominant . PP x pp = all purple flowers. if it would be Pp x pp
there is a chance of it being a white flower.
9. Define random event, and explain why it is significant that allele segregation during meiosis and fusion of gametes at fertilization are random events.
Random event s are independent of one another. allele segregation during meiosis and fusion of gametes at fertilizationare random events becuase alleles dont depend on each other on where they go when they seperate.
13. State, in their own words, Mendel's law of independent assortment.
Each allele pair segregates independently of otherngen pairs durig gamete formation.
14. Use a Punnett square to predict the results of a dihybrid cross and state the phenotypic and genotypic ratios of the F2 generation. Got it
16. Give an example of incomplete dominance and explain why it is not evidence for the blending theory of inheritance.
When red snapdragons are crossed w/ white snapdragons all f1 hybrids have pin flowers. Incomplete dominance is not soppurtfor the blending theory of of inheritance b/c alleles mantian their integrity in the heterozygote and segregation durin gamete formation. Red & whie appear in the f2 generation.
17. Explain how the phenotypic expression of the heterozygote is affected by completedominance, incomplete dominance and codominance.
complete dominance will show the dominant characetristic, incomplete will show characteristics that are mixed (ex. red and white will show pink), and codominance will show both characteristics(red and white all over)
18. Describe the inheritance of the ABO blood system and explain why the IA and IB alleles are said to be codominant.
ABO blood group is an example of a locus w/ 3 alleles. IA & IB are codominant b/c they are expressed in heterozygotes.
19. Define and give examples of pleiotropy.
Pleitrophy - the ability of a single gene to have multiple phenotypiceffects.9e.g. sickle cell anemia)
20. Explain, in their own words, what is meant by "one gene is epistatic to another."
If one gene suppresses the phenotypic expression of the other.
23. Describe how environmental conditions can influence the phenotypic expression of a character.
Enviroment influences the phenotypic expressionof gene, so that a single genotype may produce a range of phenotypes.
24. Given a simple family pedigree, deduce the genotypes for some of the family members.
see page 195 in instructor's guide.
CHAPTER 15 OBJECTIVES
After reading this chapter and attending lecture, the student should be able to:
4. Define linkage and explain why linkage interferes with independent assortment.
linkages are genes that are found on the sane chromosome (inheritance together) and do not assort independantly(b/c chromosome doesn't split)
6. Explain how crossing over can unlink genes.
during mieosis crossing iver occures , resulting in gene exchanges this unlinks the genes to transfer to the other homologous chromosome and relinks.
10. Describe sex determination in humans.
sex determination is found in the 23 chromosome. xx = a girl and xy = a boy. the sex will always be determine whether the father gives a x or y chromosome.
11. Describe the inheritance of a sex-linked gene such as color-blindness.
sex linked genes are commonly applied to genes on the x chromosome
12. Explain why a recessive sex-linked gene is always expressed in human males.
b/c females, having xx will always have 2 alleles for each trait where guys having xy have some alleles without an allele sharing the trait, since the y chromosome is smaller.
14. Distinguish among nondisjunction, aneuploidy, and polyploidy; explain how these major chromosomal changes occur and describe the consequences.
Non disjunction - mitotic/mieotic error where a homologous chromosome fails to seperate. In mieotic it can occure in mieosis 1 where the homologous pair doesnt seperate or during mieosis II & mitosis where chromatid sis don't seperate. results in abnormal # of chromosomes in duaghter cells.(ex: normally each will have an equal amount of genetic info but in miosis 1 d. cell will have 3/4 of info and the other1/4 of info) Polyploidy- a chromosome that that has more than 2 complete chromosome sets-triploid cuased by abnormal diploid egg produced by nondisjunction of all chromosomes tetraploidis when a diploid zygote undergoes mitosis w/out cyto kinesis. Anueploidy-having an abnormal # of certain chromosomes -when a normal gamete joins a 'nondisjunctional' gamete which cuase characteristic symptoms in survivors
16. Distinguish among deletions, duplications, translocations, and inversions.
Deletions are deficiencies cuased by chromosomes which lose a fragment loosing a centromere. Duplication are fragments w/out centromeres that join to a homologous chromosome.
Translocation are fragments w/out centromeres that join to a nonhomologous chromosome.
Inversion is when fragment returns to original chromosome in reverse order.