Chapter 11: Cellular Reproduction Figure 11.31 Chapter 11 ...

[Pages:4]Chapter 11 The Continuity of Life: Cellular Reproduction

Chapter 11: Cellular Reproduction

Figure 11.31 ? Audesirk2 & Byers

What is Cellular Reproduction?

Answer: The division of a parent cell into two daughter cells

Requirements of Each Daughter Cell: 1) Necessary genomic information (DNA) 2) A complete assortment of cytoplasmic materials

Cell Types Differ in Reproductive Process: A) Prokaryotes = Binary Fission

Chapter 11: Cellular Reproduction

Cell Types Differ in Reproductive Process: A) Prokaryotes = Binary Fission ("splitting in two")

? Prokaryote DNA: ? Single circular chromosome ? Attached to cell wall

Steps in Binary Fission: 1) Chromosome replicates 2) Cell elongates (membrane production) ? Chromosomes pulled apart 3) Membrane pinches in middle 4) Daughter cells formed

Can be rapid process (~ 20 minutes)

Figure 11.2 ? Audesirk2 & Byers

Chapter 11: Cellular Reproduction

Figure 11.1 ? Audesirk2 & Byers

Cell Types Differ in Reproductive Process: B) Eukaryotes

1) Mitosis: Daughter cells genetically identical to parental cell ? Functions: A) Growth (we all start as a single cell...) B) Maintenance (skin flakes off...) C) Repair (wounds heal...) D) Asexual reproduction (produces clone of parent...)

Chapter 11: Cellular Reproduction

Figure 11.3 ? Audesirk2 & Byers

Cell Types Differ in Reproductive Process: B) Eukaryotes

Cell Cycle: The cell activity from one cell

division to the next

1) Mitosis: Daughter cells genetically identical to parental cell

Interphase (majority of time):

Cancer = Signal Failure

1) G1 Phase (Growth phase 1) ? Acquire materials ? Grows

2) S Phase (Synthesis phase) ? Replicate DNA

3) G2 Phase (Growth phase 2) ? Synthesize material for cell division

? Metabolically active ? No division

During G1 phase, cell is sensitive to signals:

S Phase

G0 Phase

Chapter 11: Cellular Reproduction

Figure 11.3 ? Audesirk2 & Byers

Cell Types Differ in Reproductive Process: B) Eukaryotes

Cell Cycle: The cell activity from one cell

division to the next

1) Mitosis: Daughter cells genetically identical to parental cell

Mitotic Cell Division:

One copy of DNA and half of cytoplasm distributed to two (2) daughter cells

1) Mitosis ? Division of DNA

2) Cytokinesis ? Division of cytoplasm

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Chapter 11: Cellular Reproduction

How is DNA in Eukaryotes Organized?

Answer: DNA is packaged into chromosomes

Chromosomes contain: 1) Linear DNA strand 2) Histones (Packaging proteins)

Chromosome condensed only during cell division; extended other times (chromatin)

Centromere

Sister Chromatid

Separated at mitosis

Sister Chromatid

When condensed, DNA has already replicated ? Identical copies; connected at centromere

Figure 11.4 ? Audesirk2 & Byers

Chapter 11: Cellular Reproduction

DNA Organization: ? Chromosomes often occur in pairs called homologues ("to say the same thing") ? Both members are same length and contain same genes in same order

gEeynee

gEeynee

Diploid: Cells with pairs of homologous chromosomes (2n)

? Found in most cells of human body

Haploid: Cells with only one of each type of chromosome (n = haploid number)

? Found in sex cells (e.g., sperm / egg)

Karyotype: Entire set of chromosomes from a single cell

Human Karyotype:

Haploid Number: n = 23

Diploid Number: 2n = 46

(23 pairs)

Sex Chromosomes:

X and Y

Female = XX Male = XY

Organism Diploid # (2n)

Human

46

Gorilla

48

Cat

38

Shrimp

254

Potato

48

Figure 11.9 ? Audesirk2 & Byers

Chapter 11: Cellular Reproduction

Figure 11.3 ? Audesirk2 & Byers

Cell Types Differ in Reproductive Process: B) Eukaryotes

Cell Cycle: The cell activity from one cell

division to the next

1) Mitosis: Daughter cells genetically identical to parental cell

Mitotic Cell Division:

One copy of DNA and half of cytoplasm distributed to two (2) daughter cells

1) Mitosis ? Division of DNA

2) Cytokinesis ? Division of cytoplasm

Process of Mitosis:

Chapter 11: Cellular Reproduction

Figure 11.10 ? Audesirk2 & Byers

Phase 1: Prophase

Nuclear envelope breaks down

Centrioles: Anchor microtubules

? Chromosomes condense ? Spindle microtubules form ? Chromosomes captured by spindles (kinetochore)

Phase 2: Metaphase ? Chromosomes line up along

cell equator ? Kineticore ,,tug-o-war

Process of Mitosis:

Chapter 11: Cellular Reproduction

Figure 11.10 ? Audesirk2 & Byers

Phase 3: Anaphase

? Sister chromatids separate ? Sister chromatids move to

opposite poles ? Kineticore motors

Centrioles: Anchor microtubules

Phase 4: Telophase

? Spindle microtubules disintegrate ? Nuclear envelops (re)form ? Chromatids relax (expand)

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Chapter 11: Cellular Reproduction

Chapter 11: Cellular Reproduction

Figure 11.3 ? Audesirk2 & Byers

Cell Types Differ in Reproductive Process: B) Eukaryotes

Cell Cycle: The cell activity from one cell

division to the next

1) Mitosis: Daughter cells genetically identical to parental cell

Mitotic Cell Division:

One copy of DNA and half of cytoplasm distributed to two (2) daughter cells

1) Mitosis ? Division of DNA

2) Cytokinesis ? Division of cytoplasm

Chapter 11: Cellular Reproduction

Cytokinesis in Animal Cells: ? Microfiliments form ring around cell equator and contract to pinch cytoplasm into two parts

Chapter 11: Cellular Reproduction

Cytokinesis in Plant Cells: ? Stiff cell walls of plant cells do not allow for cells to divide by pinching at the ,,waist 1) Carbohydrate-filled vesicles line up on cell equator 2) Cells fuse, producing cell plate 3) Fusion continues until new cell wall divides cell

Figure 11.11 ? Audesirk2 & Byers

Figure 11.12 ? Audesirk2 & Byers

Chapter 11: Cellular Reproduction

Figure 11.27 ? Audesirk2 & Byers

Cell Types Differ in Reproductive Process:

B) Eukaryotes

1) Mitosis 2) Meiosis: Daughter cells contain ? the genetic information of parental

cells ? Sexual reproduction (produces gametes)

Chapter 11: Cellular Reproduction

What is the Advantage to Sexual Reproduction?

Answer: Allows for reshuffling of genes to produce genetically unique offspring better suited to environment...

Mutations in DNA are source of genetic variability: ? Allele: Alternate form of a given gene (e.g., eye color)

Eye color

Blue Allele

Brown Allele

Green Allele

Most genes have two or more alleles

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Chapter 11: Cellular Reproduction

Reshuffling Genes (Alleles) to Benefit Organism - Example:

Motionless Allele

Freezes when predator approaches

Bright Allele

Coloration stands out

Motion Allele

Moves when predator approaches

Camouflage Allele

Coloration blends in

Sexual Reproduction

Asexual Reproduction

Dinner

Motionless Allele

Freezes when predator approaches

Camouflage Allele

Coloration blends in

Asexual Reproduction

Dinner

Chapter 11: Cellular Reproduction

Figure 11.18 / 11.21 ? Audesirk2 & Byers

Cell Types Differ in Reproductive Process:

B) Eukaryotes

1) Mitosis

2) Meiosis: Daughter cells contain ? the genetic information of parental

cells

? Begin with: Parent diploid cell (2n = 46) ? Finish with: Four daughter haploid cells (n = 23)

Table 11.1

Similar to mitosis except cell goes through two nuclear divisions:

A) Meiosis I: Homologous chromosomes pair up separate (2n n)

Paternal chromosome Maternal chromosome

Chiasma: Region where paired chromosomes joined

Prophase I

Metaphase I

Anaphase I

Telophase I

Chapter 11: Cellular Reproduction

Figure 11.21 ? Audesirk2 & Byers

Cell Types Differ in Reproductive Process: B) Eukaryotes

1) Mitosis: 2) Meiosis: Daughter cells contain ? the genetic information of parental

cells

B) Meiosis II: Sister chromatids separate (mitosis revisited...)

Prophase II

Metaphase II

Anaphase II

Telophase II

Chapter 11: Cellular Reproduction

Figure 11.30 ? Audesirk2 & Byers

How Meiosis Produces Genetic Variability: 1) Shuffling of homologous chromosomes creates new combinations of

chromosomes:

During metaphase I:

2n = 6

Potential results of meiosis I:

2n = 23 = 8

Humans = 223 = 8 million

Chapter 11: Cellular Reproduction

How Meiosis Produces Genetic Variability: 2) Crossing over creates chromosomes

with new combinations of genes

3) Fusion of Gametes adds further variability:

Example - Humans Sperm = 8 million unique gametes

Egg = 8 million unique gametes Fusion = 6 trillion possibilities

Figure 11.22 ? Audesirk2 & Byers

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