Sexual Reproduction

The connection between the continuity of life and the

diversification of living things!

Review of Meiosis

•When does crossing over occur?•Which is more like mitosis—meiosis I or II?•When do homologous chromosomes separate?•When do sister chromatids segregate?

Review:• What are 3 ways meiosis increases

variation?

Crossing over…

• When does it occur?• What does it allow?• What did the Sordaria

lab show about frequency of crossing over?– Genes closer to

centromere– Genes closer to tips of

chromosomes

Terminology and Mendel’s Law of Segregation

• Male vs. Female• Key Terms:

homologous chromosomes, autosomes, sex chromosomes

• Chromosome Number– Diploid 2n– Haploid n– In Humans?

Modification of Chromosome Balance

• Aneuploidy

• What are two ways a cell can end up with an inbalance of chromosomes?

Is aneuploidy always bad?

• Polyploidy-can lead to speciation of plants

• How might plants get an extra set of chromosomes?

Modification of Gene Expression at the chromosome level

• Chromosomal Mutations• Modification of DNA within chromosomes and

genomic imprinting (epigenetics)

X vs. Y chromosomes

•Do all animals have X and Y chromosomes?

X-inactivation

• Barr body• Role of Methylation• Connection to development…when does this happen?

Mendel’s Law of

Independent Assortment

Practice Essay

• Two forms of cell division have evolved. Both have similar mechanisms, however they differ in their overall outcome.– Discuss the similarities and differences between the

two forms of cell division in terms of chromosome number and arrangement.

– One form of cell division is essential to the diversity of living things. Explain multiple ways that this process has dramatically impacted the diversity of life.

Quiz…Mendel’s Laws and Chromosomal Inheritance

• Mendel didn’t really understand chromosomes…he just observed patterns. Explain to Mendel:– How his Law of Segregation leads to balance of

chromosomes and how this balance can be upset

– How his law of Independent Assortment allows so many possibilities from just one mating!

Animal Reproductive Systems

• Big Ideas 2 & 4: Organization of human reproductive system– Organ system level– Cellular level

• Structure meets function in the human reproductive system– Organ Level– Cellular Level

Homeostasis in Reproductive Systems

• Hormonal Control of the testes--Negative Feedback

• Using the same hormones with different targets to control the menstrual cycle

• Hormonal Control of Breastfeeding and Birth--Postive Feedback

• Effects of artificial hormones on these feedback systems

Human Reproduction--Male

• Campbell’s Activity 46A

• Know the major tissues involved.

• Explain the role of structure and function in the testis

• Critical Thinking Question: How does a vasectomy work?

Human Reproduction--Female

• Campbell’s Activity 46B• Know the major tissues

involved.• Explain the role of the

oviducts (fallopian tubes).• Explain how the structure of

the oviduct allows for function.

• Critical thinking question--Why is a woman most likely to get pregnant only 2-3 days a month?

Cellular Organization:Compare and Contrast

Spermatogenesis & Oogenesis

Regulation in Males

• GNnRH• FSH• LH

Describe the negative feedback

How could taking anabolic steriods affect this system?

Regulation in females

• Role of – LH--lutenizing

hormone

– FSH--follicle stimulating hormone

How do estrogens and progesterones relate?

Role of Birth Control in Altering

Menstrual Cycle• How does birth control

“the pill” work?• How do other forms of

pregnancy prevention compare?

• What are concerns of life-long use of birth control?

Hormonal Regulation of Birth and Breastfeeding

• How is this an example of positive feedback?

• Why might positive feedback be necessary (vs. negative feedback)?

• How could labor be induced if a woman was beyond her due date?

Fertilization--An example of structure meeting function

In vitro fertilization…and the ethics of cloning

• What is IVF?• What is the goal of

large animal cloning?– GMO’s

• What are stem cell therapies?

Oh Dolly!

• Large Animal Cloning:– Purpose– Methods– Problems

Telomerase

Stem Cells: Therapeutic

cloning technology

Have we solved the embryonic stem cell problems?

Brave New World

• In what ways has biotechnology brought us into a Brave New World of human reproduction?

• What are the ethical considerations?

Unity and Diversity of

Sex in Animals

Hermaphroditic– Some Lizards

– Worms

Asexual vs. Sexual

When is it an advantage to be asexual?

When do organisms exhibit a sexual lifecycle?– parthogenesis

– Stickleback fish

– insects

Quiz Yourself…

• How does the organization of either the male or female reproductive system allow for the function?

• How is reproduction regulated and can this natural regulation be affected?

• Is sex always an advantage? What is a case where it might not be advantageous for an animal to reproduce sexually?