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CHAPTER 11: ILUSTRATED. Felipe Rodríguez

The Cell Cycle

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This presentation was done by me in 2010. The source of the images is written in the second slide

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Page 1: The Cell Cycle

CHAPTER 11: ILUSTRATED.

Felipe Rodríguez

Page 2: The Cell Cycle

All Images taken form:Audeirk, D. Audesirk, J & Byers, B. (2008) Biology with Physiology: Life on Earth. New Jersey. : Pearson.

Page 3: The Cell Cycle

ASEXUAL REPRODUCTION.

(a) Paramecium sp. Is a protists, a microorganism.

(b) Yeast, a unicellular fungus reproduces asexually.

(c) Hydra a sea animal, reproduces a sexually. It starts growing a bud until it grows big enough to be an independent organism.

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PROKARYOTIC CELL CYCLE.

Prokaryotic Cell Cycle consist of DNA growth and former cell division.Cell Division in Prokaryotic cells is called BINARY FISSION.

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EUCARYOTIC CELL CYCLE.

This cycle consist of the following main phases:1. Interphase(Yello

w).2. Cell Division

(Light Blue).Interphase has 4

phases: G1,G0, S and G2.

Cell Division could be either:

Mitosis or Meiosis

Page 6: The Cell Cycle

CHROMOSOME.

A human chromosome consist of a single DNA double helix and some proteins called Histones and scaffolds.Chromosomes are a compact DNA container.

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CHROMOSOME.

These are the main features of chromosomes:1. Genes:

sequences of DNA that have an specific function.

2. Centromere: it joins two parts of the chromosome, it does NOT have to be at the center.

3. Telomeres: the “end” of the chromosome, they maintain the equilibrium and seal the chromosome’s material.

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DUPLICATED CHROMOSOME.

A duplicated chromosome consist of two identical chromosomes.

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KARYOTYPE.

A karyotype is the full set of chromosomes located at each cell of an organisms. All this chromosomes are located at the nucleus.They consist of homologues pairs. For example, chromosome 1 consists of two identical chromosomes. They share the same genes at the same order and the same length. Exception: sexual chromosomes.This photo is from a male, since it has XY, if it were from a women’s it would be XX.

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MITOTIC CELL DIVISION.

Prophase:•Chromosomes condense.•Microtubules form.•Nuclear Envelop disintegrates.•Spindle Microtubules grab the chromosomes.Metaphase:•Spindle Microtubules align the chromosomes along the cells’ “Equator”.

Page 11: The Cell Cycle

MITOTIC CELL DIVISION.

Anaphase:•Sister chromatids are separated and moved to opposite sides of the cell. Microtubules push each pole apart.Telophase:•Microtubules start extending, nuclear envelop reforms and spindle microtubules disappear.

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CYTOKINESIS: ANIMAL CELLS.

Microfilaments attached to the plasmas membrane start contracting the cell’s Equator, until it divides in two.

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CYTOKINESIS: PLANT CELL.

During Cytokinesis in plan cells, once the cell is divided , the Golgi Apparatus starts sending vesicles with carbohydrates (cellulose) to start creating a cell wall in-between both daughter nuclei.

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CELL CYCLE CHECKPOINTS.

Checkpoints throughout the cell cycle:•After G1 : Is your DNA suitable and intact for it to synthesize?•After G2: Has DNA replication successfully occurred?•After Metaphase: Are all the chromosomes aligned at the Equator?

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FIRST CHECKPOINT.

Cycling-dependent kinases are proteins that are assigned to control the progress of the cell cycle.

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ALLELES.

Homologues have same of different Alleles. Alleles are variations of the same gene, that determine different characteristics.

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MEIOTIC CELL DIVISION.

Both members of a pair of homologues chromosomes are replicated before Meiosis. One chromosome is parental and the other is maternal.

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MEIOSIS I.

After MEIOSIS I, each daughter cell receives one of each pair of homologues chromosomes.

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MEIOSIS II.

After MEIOSIS II, sister chromatids separate into independent chromosomes and each daughter cell receives one of these chromosomes.

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MEIOSIS I.

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CROSSING OVER.

Crossing Over occurs at Prophase I and it adds genetic diversity to the chromosomes.

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METAPHASE I.

Homologues chromosomes are paired up taking as a reference the Equator. Each PAIR of chromatids gas a single functional kenitochore.In MITOSIS, each sister chromatids have one kenitochore.

Page 23: The Cell Cycle