Cell Division Ppt

  • Uploaded by: Mandy Westbrooks Miller
  • 0
  • 0
  • December 2019
  • PDF

This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA


Overview

Download & View Cell Division Ppt as PDF for free.

More details

  • Words: 536
  • Pages: 27
Genetic Information 

 



Genetic information is carried on genes A gene is… 1 molecule of DNA contains thousands of genes DNA=chromatin when the cell is not dividing (not visible under a microscope)

Mitosis 

http://www.johnkyrk.com/mitosis.html

Chromosome Structure 



DNA (chromatin) replicates at during cell division preparation = 2 identical chromatids 2 chromatids coil, condense and join together at the centromere = chromosome (now visible under a microscope)

Chromosome Number 





Every species has a characteristic # of chromosomes Chromosomes occur in pairs (code for same info – one from ea. Parent) = homologous pairs A cell that contains both members of the homologous pair are called diploid – 2N

Chromosome Number cont. 



A cell that contains only one member of the homologous pair is called haploid – 1N In humans:  

Diploid number is 46 (somatic cells) Haploid number is 23 (gametes)

Frequency of cell division 

Varies drastically among different cell types    

Bacteria – every 20 minutes Human embryo - 15-20 minutes Human skin – every 2 weeks Liver cells – approx. every 18 months

Frequency of cell division 

Some cells do not divide after a certain age   

Liver cells Intestinal cells Nerve cells

Type of cell division 

Asexual



Sexual

Asexual Reproduction   

Making of new cells by mitosis Offspring are exact replica of parent Only one parent 

Occurs in: 





Unicellular organisms as a means of reproduction Lower plants and animals as a means of reproduction Most somatic cells of multi-cellular organisms

Asexual Reproduction 

Advantages     

Simple Fast Low energy output Large number of offspring Daughter cells are identical to parent cells

Asexual Reproduction 

Disadvantages 

No variation among offspring

Sexual Reproduction  





Making of new gametes by meiosis Involves the combining of gametes from 2 different parents Gametes fuse to form a zygote (fertilized egg) Chromosome number in gametes is 1N to ensure constant chromosome number on future generations.

Sexual Reproduction 

Advantages 

Variation among offspring

Sexual Reproduction 

Disadvantages    

More complicated Must find mate High energy cost Fewer offspring (generally)

The Cell Cycle 





The life of a eukaryotic cell is diagramed as a cell cycle A repeating sequence of growth and division 5 phases

The Cell Cycle 

Interphase : 3 phases 

G1 Phase:



S Phase :



G2 Phase:

The Cell Cycle 

Mitosis - NUCLEAR DIVISION -4 phases 

Prophase:    

Centrioles Spindle fibers Nucleolus Nuclear membrane

The Cell Cycle 

Metaphase 

Fibers push chromosomes to line up along the equator of the cell

The Cell Cycle 

Anaphase 

Fibers shorten and pull chromatids apart to opposite sides of the cell.

The Cell Cycle 

Telophase    

Spindle fibers Chromatids Nuclear membrane nucleolus

The Cell Cycle  

Cytokinesis: CYTOPLASM DIVISION Not a phase of mitosis    

Cytoplasm and organelles separate Usually begins in early anaphase Cytoplasm pinches in In plant cells, a new cell wall is formed between the 2 new cells – cell plate

Related Documents

Cell Division Ppt
December 2019 25
Cell With Cell Division
April 2020 19
Cell Division
May 2020 8
Cell Division
December 2019 16
Cell Division
July 2020 17
Cell Division
November 2019 26

More Documents from ""

Daily Planner
December 2019 29
Energy Changes
December 2019 18
Meal Planner
December 2019 20
Cell Division Ppt
December 2019 25
December 2019 42
Herbal Abortion
August 2019 31