01-MitosisMeiosisS11b - How do organisms get from one cell...

Info iconThis preview shows pages 1–14. Sign up to view the full content.

View Full Document Right Arrow Icon
How do organisms get from one cell to billions or trillions??? CELL DIVISION!! How do organisms repair themselves? CELL DIVISION!!
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
What happens if cell division is uncontrolled ? Something undesirable! For example, melanoma, a type of skin cancer caused by uncontrolled growth of melanocytes.
Background image of page 2
Cell Division Ø Cellular reproduction is a key element of life Ø Requires 3 things: 1) Replication of genetic materials 2) Accurate segregation of genetic materials 3) Division of cytoplasm Ø Process needs to be controlled Ø Responsive to environmental conditions
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Prokaryotic cell division Ø Prokaryotes have simple form of cell division: Binary fission Ø Is clonal( : produces two identical cells Ø They also have a simple DNA: single circular chromosome Ø Chromosome must be compacted, folded to fit into the cell Ø Complex with proteins Ø DNA is compacted by topoisomerases allow dna to segregate
Background image of page 4
Bacteria Divide by Binary Fission Ø DNA must be replicated and segregated into different ends of cell prior to cell division Ø DNA replication and segregation a concerted process and coupled Ø Replication begins at unique site: origin of replication Ø Bidirectional to unique site: terminus
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Fig. 10.1 Origin of replication Replication (bidirectional) Terminus of replication Segregation FtsZ production Septum formation
Background image of page 6
Binary Fission Ø Segregation once thought to be passive Ø Replicated DNA actively partition to different ends of cell Ø Requires specific sequences near origin Ø Growth of new membrane and a septum partitions of other cell contents Ø Septum( forms at site of ring of FtsZ protein Ø FtsZ resembles microtubule protein tubulin XÄÜÁ ª* involved in eukaryotic mitosis
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Fig. 11.3 Figure 10.2 Fluorescent micrograph of FtsZ protein
Background image of page 8
Eukaryotic chromosomes Ø Sister chromatids : 2 copies of the DNA within the replicated chromosome Ø Homologue : same chromosome diff. parent Ø Centromere : visible constriction Ø Short repeated DNA sequences Ø Kinetochore( : proteins attached to centromere Ø Connect chromosomes to microtubules during mitosis Ø Cohesin ¨ ÂÜÁ ª * : complex of proteins holding sister chromatids together
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Eukaryotic chromosomes Figure 10.7
Background image of page 10
Problems for Eukaryotic Cells Ø Chromosome compaction Ø Strands of DNA are too long to fit into cell Ø must always be compacted Ø even greater compaction for separation Ø Replication and chromosome separation occur at different times Ø chromosomes are not labeled Ø Means must keep chromatids of chromosomes attached until separation Ø Release of attachment is irreversible( Ø Cleavage of cohesin
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Eukaryotic DNA Compaction Ø Compaction of strands of DNA: Ø DAN is compacted with histone protein Ø There are multiple levels of compaction 1. Nucleosome DNA wrapped around a core of 8 histone protein(histone octamer) Ø Nucleosomes are spaced ~200 nucleotides apart along the DNA
Background image of page 12
Nucleosome compaction Figure 10.5
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 14
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/29/2011 for the course BIO 110 taught by Professor Bos during the Spring '10 term at Purdue University-West Lafayette.

Page1 / 55

01-MitosisMeiosisS11b - How do organisms get from one cell...

This preview shows document pages 1 - 14. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online