Transcript Cell Division

CELLS AND CELL DIVISION
Kani Shiwani, Vee Duong, Vilma Arceo
B2
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Cell Division
• Process in which the parent cell
distributes its DNA and other
genetic material into two daughter
cells
• Cell Cycle – the series of events
that take place leading to cell
division that produces two daughter
cells
– Interphase: G1, S, G2
– Mitosis – genetic material
of cell divides
– Cytokineses – cell
membrane/ wall divides
Human melanoma cell dividing
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Types of cell division
• Mitosis - process of making new body cells
– Repairing of damaged cells
– Growth
• Meiosis – used to create gametes (egg and
sperm cells)
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Mitosis
• Used for growth and repair
• Chromosomes are duplicated and then separated
into two identical daughter cell
– each with its own nucleus
• Stages:
– Prophase – DNA condenses, centrioles appear to form
mitotic spindle
• Prometaphase – chromosomes join together at the
centromeres
– Metaphase – sister chromatids line up along the
metaphase plate
– Anaphase – sister chromatids are separated by
kinetochores
– telophase - nucleus separates, nuclear envelope
regenerates, chromosomes decondense
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Mitosis
Meiosis
• Used to make sex cells
• Parent cell divides to form cells with half
their genetic material
• Produces haploid cells that are not identical
to each other or the parents.
• Two phases: Meiosis I & Meiosis II
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Meiosis I
• Prophase I – synapsis occurs (joining of
homologous chromosomes along their length);
crossing over occurs at chiasmata -> genetic
variation
• Metaphase I – genetic variation when
homologous chromosomes randomly line up
(independent assortment)
• Anaphase I – homologous chromosomes
separate
• Telophase I – homologous chromosomes
separate and gather at opposite poles
Meiosis I
Meiosis II
• Prophase II – spindle reforms
• Metaphase II – sister chromatids arranged
along metaphase plate randomly
• Anaphase II – sister chromatids are pulled
apart from each other
• Telophase II – chromosomes move to
opposite ends and nuclei reappear
Meiosis II
Mitochondria
• A membrane-bound organelle
found in most eukaryotic cells.
• Take part in cellular metabolic
processes
• Supply energy for the cell
• Double bound organelle
• Made of phospholipid double
layers & proteins
• Have their own genome
Golgi Apparatus
• Modify, sort and package proteins
• Transport of lipids
• Receives substances from ER
• Collection of flattened membrane sacks called cisternae
Cell wall
• Rigid and strong
• Protects the cell
• Made of cellulose
Endoplasmic Reticulum
• Manufactures substances
• Smooth ER: contains
enzymes, manufactures fats
and steroids
• Rough ER: has ribosomes,
manufactures proteins
• Transports substances to be
exported
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Lysosome
• Sac like structures
• Digest substances
• Release enzymes to break down complex
molecules
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FRQ
2011 FRQ
During an investigation of a freshwater lake, a sad AP biology student discovers
a previously unknown microscopic organism. Further study shows that the
unicellular organism is eukaryotic.
http://apcentral.collegeboard.com/apc/public/repository/ap11_biology_scoring_g
uidelines.pdf
a. Identify FOUR organelles that should be present in the eukaryotic organism
and describe the function of each organelle
b. Prokaryotic cells lack membrane-bound organelles found in eukaryotes.
However, prokaryotes must perform many of the same functions as eukaryotes.
For THREE of the organelles identified in part (a) explain how prokaryotic cells
carry out associated functions.
c. According to the endosymbiotic theory, some organelles are believed to have
evolved through a symbiotic relationship between eukaryotic and prokaryotic
cells. Describe THREE observations that support the endosymbiotic theory.
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Scoring Key
a) Identify organelle (1 point for listing 4); describe
corresponding function (1 point for each function) = 5
points maximum
b) Organelles identified in part a – 1 point for each
associated function = 3 points maximum
c) General description of endosymbiotic theory – 1 point;
Observations for endosymbiotic theory – 1 point for each
= 4 points maximum
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2006 FRQ
A major distinction between prokaryotes and eukaryotes is the presence of
membrane-bound organelles in eukaryotes.
http://apcentral.collegeboard.com/apc/public/repository/_ap06_biology_sg.pdf
a. Describe the structure and function of TWO eukaryotic membrane-bound
organelles other than the nucleus.
b. Prokaryotic and eukaryotic cells have some non-membrane-bound
components in common. Describe the function of TWO of the following and
discuss how each differs in prokaryotes and eukaryotes.
– DNA
– Cell wall
– Ribosomes
c. Explain the endosymbiotic theory of the origin of eukaryotic cells and discuss
an example of evidence supporting this theory.
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Scoring Key
a) Organelle Structure – 1 point for each (2 organelles – 2
points total); Organelle Function – 1 point for each (2
points total) = 4 points max
b) Common component between prokaryotes and
eukaryotes (2); Function – 1 point for each; Difference
between prokaryotes and eukaryotes – 1 point = 4
points max
c) Explanation for the endosymbiotic theory – 1 point;
Evidence supporting the theory – 1 point = 2 points max
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THE END
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