Download Summer BIO 152F How do cells divide? mitosis and meiosis

Summer BIO 152F
How do cells divide?
mitosis and meiosis
Lectures 9&10
May 31st 2005
Outline
• Context and connectionsevolution & genetics
• Prokaryotic cell division
• Eukaryotic cell division:
– Mitosis
– Meiosis
1
Cornerstone of evolution
† Inheritance of variable traits leading
to a difference in reproductive
success.
† All organisms are related-- common
ancestry
† Organisms have changed over time
[Cell theory pattern and process]
† All organisms composed of cells and
cells arise from other cells
2
† Ultimate questions & explanations =
WHY? (Evolutionary context)
† Proximate questions & explanations=
HOW? (includes what, where, when)
Proximate explanation
† Variability
† Inheritance
3
Topics
† What is the hereditary material?
† How is the hereditary material
duplicated?
† How is the hereditary material passed
on to the next generation?
† How is variation generated?
Working backwards
† First, we will look at cells.
† Common features
† Differences
4
Cell types—Fig 1-5
† Prokaryote
† Eukaryote
„ Note the difference in size and structure
„ Prokaryotes are smaller and do not have
a nucleus
Cell division
† In unicellular organisms, cell division
equals reproduction.
† In multicellular organisms, cell division is
important in the growth and maintenance
of tissues as well as in reproduction.
† Process works best when new cells are an
exact copy of the old. But this process
does not always proceed according to
plan…..
5
Bacterial cell division
• Fig 11-6
Eukaryotic cells divide by
mitosis and meiosis.
† The CELL CYCLE is regulated, including
entry into mitosis.
† Entry into meiosis is also regulated.
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Next few slides were from text:
11.16 cell cycle
11.7 closer look at chromosomes
11.8 overview of mitosis
11.9 mitosis and cytokinesis
6
Mitosis-ultimate questions
† What is the significance of mitosis?
„ Heritability
„ Variability
† What is the consequence of error?
Reproduction
• Of eukaryotic organisms
• (We will look at prokaryotic organisms
Thursday)
7
Eukaryotic life cycle
haploid (1n)
Meiosis
Fertilization
diploid (2n)
Meiosis:
† the reduction process in which a
diploid cell produces four haploid cells
over two divisions
† Overview of important steps
† Figures-12.3; 12.4 [you learn the
steps I will focus on the significance
to variation and inheritance]
8
Summary
† Prokaryotes have a simple mode of
cell division - no mitosis or meiosis
† In eukaryotes, mitosis results in
cells that are identical or nearly so.
† In meiosis, homologous
chromosomes pair and exchange
segments (genetic recombination).
Chromosome content is halved.
Meiosis: ultimate questions
† What is the significance of meiosis?
„ Heritability
„ Variability
† What is the consequence of error?
9
Bacteria-lab 3
Useful readings in the text:
„ Bacterial diseases- pp583-84 (Chap 27)
„ Essay Antibiotics and evolution of
resistance
„ Reproduction and inheritance:
„ Box 27.1
„ Box 19.1 (plasmids—including Fig 19.2)
„ Also- essay p 358 Ch 16 antibiotics that poison the
ribosome
„ Lateral gene transfer p432
Readings for this section
† Chapter 12—all
† Chapter 11 pp227 -230; 11.2 (pp
232-236)
† More readings about mutation later
† Basic genetics-Chapter 13 (some
sections)
10
How do you study this?
† NOW:
„ Make a list of important terms-know what they
are and how they are connected.
„ Learn the stages of mitosis & meiosis
„ Know how they are similar, different, when they
occur,
† By the end know the consequence of error
at each step
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