Class Notes (835,045)
United States (324,024)
BIO 201 (90)
Lecture 30

BIO 201 Lecture 30: Meiosis
Premium

4 Pages
56 Views
Unlock Document

Department
Biological Sciences
Course
BIO 201
Professor
Lara Hutson
Semester
Spring

Description
BIO 201 Dr. Lara Hutson Lecture 30 Notes 4/19/17 Asexual vs. Sexual Reproduction ● Asexual ○ Fission and mitosis (budding) ■ Yeast, protists, some multicellular organisms ○ Duplication of one genome followed by cell division or budding → 2nd generation cells are genetically identical* to parents and each other ■ *assuming DNA replication is perfect ■ Very little change from generation to generation ● Sexual ○ Combine genetic material from two parents → next generation is genetically distinct from parents and from each other ○ Advantage: diversity!!! ○ Problem: how to maintain appropriate chromosome numbers from one generation to the next ○ Solution: halves genomes before combining → MEIOSIS Life Cycles of a Sexually-Reproducing Diploid ● Multicellular diploid adults (2n = 46) ● Form haploid germ cells (egg and sperm) via meiosis (n = 23) ● Coming together of egg (n) and sperm (n) (fertilization) → formation of diploid zygote (2n) → mitosis (2n) → multicellular diploid organism (2n) Meiosis I 1. A. Metaphase I: Chromosome align on Metaphase I plate. Homologs adjacent to each other (synapsis) B. Homologs exchange DNA (chiasma) 2. Anaphase I: Homologous chromosomes segregate (sister chromatids remain together!) 3. Cytokinesis I Meiosis II 4. Metaphase II: Chromosomes align on metaphase plate 5. Anaphase II: Sister chromatids separate 6. Cytokinesis II ● Independent Assortment of Chromosomes Example: ○ Diploid (2n) ○ 3 chromosomes ● Number of different combinations: (# of chromosomes) ○ (# of homologs) ○ 2 = 8 ○ All distinct gametes! ● Diploid organism, 23 chromosomes: ○ Meiosis → 2 possible genetically distinct haploid gametes (8,388,608) ○ Fertilization → (2 )(2 )
More Less

Related notes for BIO 201

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit