lesson 2 cell cycle
DESCRIPTION
cell cycleTRANSCRIPT
MODELS ALLOW US TO UNDERSTAND THE RELATIONSHIPS BETWEEN REPRODUCTION, HEREDITY AND DIVERSITY. Lesson #2
THE LIFE OF A CELL
Cell cycle
ALL CELLS HAVE A SPECIFIC FUNCTION
Can you think of some examples?
SPECIALIZED/DIFFERENTIATED CELLS
1. Specific function
2. Specific structrure
CELL LIVE, DO THEIR FUNCTION AND SOMETIMES DIVIDE…
Why do cells need to divide?
NOT ALL CELLS DIVIDE
Which cells divide?And why?
ANSWERSWHICH CELLS ??
1. Unicellular organisms (eukaryotes and prokaryotes)
2. Most specialized cells (G0) in multicelullar organisms, except some (cardiac muscle, neurons, gametes…).
3. Stem cells (non-differentiated cells which divide to produce different types of cells.)
WHY ??
4. Asexual reproduction of unicelular organisms
5. Growth multicelullar organisms
6. Increase in the amount of specific cells.
7. Regeneration or cell replacement
TWO MAIN MOMENTS IN THE CELL LIFEInterphase: development
Mitotic phase: division
CELL CYCLE
INTERPHASE During this stage the cell grows, develops more organelles, DNA is duplicated and centrosomes duplicate. The cell becomes ready for the next division.
It is the longest stage of the cell cycle
The nucleus has the usual structure
There are 3 distinguished phases during Interphase:
G1: Cell growth, organelles and cytoplasm substances duplicate
S: DNA replication
G2: Cell checks for error in replication, finishes duplicating centrosomes. Ready for division.
G0 is a stage in which the cell stops dividing and is metabolically active
Images: http://scienceaid.co.uk/biology/cell/cycle.html
MITOTIC PHASEMitosis: nuclear division
1 cell nucleus divides into 2 identical nuclei. Same DNA.
Cytokinesis: Division of the cytoplasm
EXERCISE 1 How many cells are in Interphase?
How many cells are in the Mitotic phase?
MITO
TIC
PHASE
CELL CYCLE