Cell Growth and Reproduction

Cell Size Limitations How does a cell receive materials and expel its wastes? Through the plasma membrane This means that no part of the cell can be too far away Mitochondria of a cell 20 cm wide would have to wait months

Surface Area to Volume Ratio The more volume = more cytoplasm = more energy requirements Volume increases much greater than surface area If a cell a cell were to double; it would require 8X as much nutrients

Cell Reproduction Recall cell theory One cell becomes two Chromosomes – structures which contain DNA and are carriers of genetic material that is copied and passed from generation to generation

Cell Reproduction cont… Most of time as chromatin Chromatin – long strands of DNA wrapped around proteins Condenses before cell division Cell division follows a pattern or cycle

Chromosomes

The Cell Cycle Events that occur in the life of a cell Includes 3 major stages: Interphase Mitosis Cytokinesis

Interphase Most of the cell cycle is in what stage? 3 parts G1- rapid growth and metabolic activity S – DNA synthesis and replication G2 – Cell prepares for division

Mitosis Cells undergo division when they get to a certain size Continuous process Stages are named for ease of identification

Steps of Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis

Prophase Chromatin condenses into chromosomes Two halves called sister chromatids are held together by contromere Nucleus disentegrates Centrioles go to poles Spindle forms

Prophase

Metaphase Chromosomes pulled by spindle fibers at the centromeres Sister chromatids lined up in the middle Single file

Metaphase

Anaphase Centromeres split Sister chromatids pulled apart by spindle fibers Pulled to opposite sides

Anaphase

Telophase Chromatids reach opposite poles Chromosomes unwind Spindle breaks down Nuclear membrane and nucleolus reappear

Telophase

Cytokinesis Dividing the cytoplasm between the two new daughter cells Cleavage furrow in animal cells Cell plate in plant cells

Cytokinesis in Animals

Cytokinesis in Plants

Mitosis in Onion Cell

Mitosis in Whitefish

In mitosis, the two double copies of the DNA attached to the spindle fibers are known as __________. a.  centromeres   b.  chromatids   c.  centrioles   d.  nucleoli

During which phase do most cells spend the most time? a.  prophase   b.  metaphase   c.  anaphase   d.  interphase 

If a cell has 20 chromosomes, how many chromosomes will be present in the daughter cells?

List the stages of the Cell Cycle in order

Name one stage of Interphase