BIOL 101 Lecture Notes - Lecture 19: Sexual Reproduction, Genetic Variation, Karyotype

13 views5 pages

coralwallaby975

7 Nov 2016

School

USC, SC, Carolina, South Carolina

Department

Biological Sciences

Course

BIOL 101

Professor

czako

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Concept 13. 1: offspring acquire genes from parents by inheriting chromosomes, in a literal sense, children do not inherit particular physical traits from their parents, it is genes that are actually inherited. Concept 13. 2: fertilization and meiosis alternate in sexual life cycles, a life cycle is the generation-to-generation sequence of stages in the reproductive history of an organism. Each chromosome pairs with its homolog and crossing over occurs. X-shaped regions called chiasmata are sites of crossover. Pairs of homologs line up at metaphase plate with one chromosome facing each pole (pairs are not in same plane as in mitosis) Microtubules from one pole attach to the kinetochore of one chromosome of each tetrad. Microtubules from the other pole are attached to the kinetochore of the other chromosome. One chromosome of each pair moves toward opposite poles, guided by spindle apparatus. Sister chromatids remain attached at the centromere and move as one unit toward the pole.

Related Questions

Ploidy refers to the number of complete sets of chromosomes (genes) present in a cell. The number of chromosomes in a complete set is a fixed characteristic of a species. Humans are diploid with two sets of 23 chromosomes. Fruit flies are diploid with two sets of 4 chromosomes. Sexually reproducing organisms are diploid, each somatic cell of an organism has two complete sets ("di" is a prefix indicating 2.). To complete a life cycle and reproduce new members of a species, mating is required. Mating brings a donation from a male and a donation from a female together. However, if the male and female cells remain diploid, the fertilization will result in a tetraploid zygote. In general, these are not viable. A mechanism is needed to form special haploid cells, gametes. The diploid set is split precisely into two complete haploid sets. That mechanism is meiosis.

The complete set of chromosomes of a species is also the complete set of genes of a species, the genome. (Yes, there is a minor contribution from mitochondria and chloroplasts. Inheritance of this information is "cytoplasmic".)

Please answer the following questions:

1. How many chromosomes in a brain cell of a fruit fly? How many chromosomes are in a liver cell of a human? Explain both answers.

2. How many chromosomes are in a fruit fly unfertilized egg? How many chromosomes are in a human egg? Explain both answers.

3. Why is meiosis necessary for sexually reproducing organisms? How many chromosomes are in a human zygote? Relate the two answers.

4. What is a gene allele? Suppose there is a gene called "bingo" and it is present once in a complete haploid set. How many alleles of "bingo" does a diploid individual have? How many copies or versions of the gene "bingo" are present in a diploid individual?

5. Modern DNA sequencing clearly identifies alleles by showing the different DNA sequence of each allele. These alleles may be termed structural alleles (I coined the term for this problem.). Classical genetics only dealt with phenotypes or visible traits. As a result, alleles of genes were identified by functionality, usually normal or non-functional. Using your knowledge of gene structure and gene expression, postulate a relationship between structural alleles and functional alleles. (include relative amounts; more, less, or equal).

What is a genome? What is a genome made of? Describe the bacterial genome. How do bacteria reproduce? What is binary fission? Distinguish between a chromosome and chromatin. Where are chromosomes located in eukaryotic cells? What is the chromosome made of? What is a centromere? What is the centromere's role? What are sister chromatids and how do they arise? Distinguish between somatic cells and germ (gametes) cells. Describe the cell cycle. What are the different phases? What occurs during S phase? What is interphase? How is the cell cycle controlled?

Describe mitosis. What are the phases of mitosis? What occurs in each of the phases of mitosis? What is cytokinesis? How does this differ between plant and animal cells? What is a kinetochore? Where does it form? What is its role? What is the role of microtubules in mitosis? What is a centriole and what is it composed of? What is a centrosome and what is its role in mitosis? What is the metaphase plate and why is this important? What is the mitotic spindle, its role and its makeup? What defines a diploid cell? How many copies of each chromosome is in a diploid cell? What about a haploid cell? Why do the daughter cells of mitosis always have the same complement of chromosomes?

Describe meiosis. What are the phases of meiosis? What occurs in each of the phases of meiosis? Distinguish between meiosis I and meiosis II and describe how each of these processes compare to mitosis. Why do animal cells undergo meiosis? What is a gamete? What is a zygote? What are recombination, crossing-over, and chiasma? When and why does this occur? What is meant by 'homologous pair of chromosomes'? Why don't the daughter cells of meiosis have the same genetic makeup? What controls the segregation of chromosomes into the gametes?

What are genetic characters? What are genetic traits? What is an allele? What is a locus? How many alleles at each locus would a human cell have and why? Distinguish between genotype and phenotype. What is meant by a dominant gene? What is meant by a recessive gene? How do these differ? What is the genotype of a homozygous dominant organism? What is its phenotype? What is the genotype of a homozygous recessive organism? What is its phenotype? What is the genotype of a heterozygous organism? What is its phenotype? What is a genetic cross? Distinguish between the P, F1, and F2 generations. What is a true-breeding line? What is the genotype and phenotype of a cross between homozygous dominant and homozygous recessive parents? If the F1 progeny are crossed, what would be the genotype and phenotype of the F2 generation? What would be the phenotypic ratio? What would be the genotypic ratio? Be ready to generate Punnet square tests or probability analyses of crosses involving more than one genetic locus. Describe a dihybrid cross where two alleles are homozygous dominant in one parent and homozygous recessive in the other. What would be the phenotypic ratio of the F2 generation from this dihybrid cross? What is meant by independent assortment? Be prepared to calculate probabilities resulting from different crosses.

Distinguish between complete and incomplete dominance. How would incomplete dominance alter the results of a hybrid cross? What would the resulting F2 generation phenotype and genotype ratios be? What is codominance? How does this affect the results of crosses? Be prepared to determine likely blood types of parents based on the blood types of their offspring. What is a polygenic trait? What is a carrier state for a genetic disease? What is meant by linked genes? How does this affect expected outcomes of genetic crosses? How is gene linkage used for chromosomal mapping? Distinguish between autosomes and sex chromosomes. What sex chromosomes are found in women? What sex chromosomes are found in men? What are sex-linked traits? Be prepared to give the results of crosses that involve sex-linked recessive traits. What is the process of nondisjunction? What are the likely results? Why is this important? What is a Barr body? Recognize the genetic abnormality of Downs Syndrome, Turner's Syndrome, and Klinefelter's Syndrome.

pucewallaby221

Biology lab homework

Dragon Genes

http://www.concord.org/stem-resources/modern-genetics

BLY 121L - Take HomeAssignment

Due: Start of class time âAt thestart of class next week

Answers MUST beâ¦

â¢ typed (no smaller than 11-pointfont)

â¢ complete sentences (i.e., grammaticallycorrect â AND spell check!)

â¢ THIS IS NOT AGROUP EFFORT â NO POINTS WILL BE AWARDED, IF YOUR PAPER ISSIMILAR IN CONTENT AND WORDING TO THAT OF YOURPEERâS.

Complete ALL4 modules:

1. Intro& Rules

2. Meiosis

3. Pedigree andGenes

4. The PlatesProblem

Complete and answer all of the questions fromeach module.

Introduction

Breed dragons to yield several offspring anddevelop a chart for all of the phenotypic characteristics youobserve.

â¢ Note the genotype and dominant/recessivecondition for each trait.

â¢ When you reach this section of theexercise, be sure to change the genotype for all traits to completethe chart.

Whatare the traits exhibited by yourdragons?

**YOUMUST TURN IN YOURCOMPLETED CHART AND IT MUST BE LEGIBLE!

Rules

Dominance and Recessive Traits

What isthe chromosome number(ânâ) for thedragons?

Which trait(s)exhibit incompletedominance?

What does it mean fora trait to be incompletely dominant?

Noallelic combination is described as being heterozygousrecessive. Why do you thinkthis is thecase?

Some Traits are Sex-linked

Which dragontrait(s)is/are sex-linked?

How dosex-linked traits differ from autosomal traits?

Color and Lethal Combinations

Describehow the inheritance ofcolor is different from that of horns and/orwings.

On whichchromosome is the lethal combination exhibited? What is the lethalcombination?

Meiosis

What is the phenotypeof your new dragon?

Whichtraits areinherited from the mother dragon? AND Which traits are inherited from the father dragon?

Wereany traits expressed by the offspring that differed from either or both of the parents? If so, whatwere they?

How does meiosisallow for variation inoffspring?

How doesfertilization allow for variation in offspring?

Pedigree and Genes

Now that you know how to breed dragons, let'stry some selective breeding in the pedigree view. Use the cross tool tobreed a new generation of dragons; breed two of thedragons from this new (F1) generation. Repeat thisat least8 times.

What do younotice about the dragons as you continue to breed more generations?

Use the chromosome tool to closelyexaminethe dragonsâ genes. If you had trouble answering the sex-linkedquestion above, now you can observe and compare the Xand Y chromosomesâ¦

Can you find any genesthat are different among the members of your F8generation?

How many generationsdo you have to breed until all the dragons are exactly thesame?

You arecreating an inbred strain of dragons in the final generation(s)of this process. Write a notedescribing your strain, and explain what is âspecialâ aboutall individuals in an inbred strain of organisms.

The Plates Problem

Try breedingsome offspring to see resultsof these crosses. Does thepattern of inheritance ofplates tell you anything useful?

Based on yourbreeding experiments, where might you expectto find the gene forplates (i.e., On whichchromosome might the gene be located?) Why do you think this iscorrect?

Dragons thatgrow plates usually do so quite late in their life, so dragons thathave a new baby don't know right away whether or not it will growplates. Which trait(s)exhibited by a baby might helpa mother dragon determine whether her baby will growup to have plates?

DragonGenes
Genotypes/Phenotypes

Trait	Phenotype	Genotype
Horns	Horns
	No Horns
Wings	Wings
	No Wings
Legs	4 Legs
	2 Legs
	No Legs
Tails	Fancy Tail
	Plain Tail
Fire-breathing	Fire-breathing Male
	Non-fire-breathing Male
	Fire-breathing Female
	Non-fire-breathingFemale
Color	Green Male
	Yellow Male
	Red Female
	Blue Female
	Brown Female
	Purple Female

olivedonkey40

BIOL 101 Lecture Notes - Lecture 19: Sexual Reproduction, Genetic Variation, Karyotype

Document Summary

Get access

Related Documents

BIOL 101 Lecture Notes - Lecture 21: Generation Time, Degenerative Disease, Phenylketonuria

BIOL 101 Lecture Notes - Lecture 27: Mitochondrial Myopathy, Organelle, Prophase

BIOL 101 Lecture 17: Chapter 12 Notes

Related Questions