CELLS Growth and Reproduction Mitosis

I. Structure & Function Cells that make up an organism come in a lot of sizes and shapes. Remember: Structure relates to function Journal: What does this mean?

II. Size limitations & Surface Area to Volume Ratio Surface Area to volume Ratio – As a cell grows, its surface area becomes smaller than its volume…..

The Importance of High Surface Area to Volume Ratio Diffusion of necessary nutrients into the cell DNA  RNA  Proteins

III. Characterizing Cells based on chromosome number Diploid Cells: Cells having two sets of chromosomes – Normal cells of the body are diploid – Commonly abbreviated 2n Haploid Cells: Cells that contain only one set of chromosomes – Typically reproductive cells, called gametes – Commonly abbreviated 1n

Which process produces diploid cells? Haploid cells?

DNA Chromatin: DNA that is not coiled Chromosomes: Chromatin (DNA) and proteins that are rod shaped. – Ready for cell division

Histones: proteins that help maintain the shape of chromosomes and aid in the tight packing of DNA

Chromosome structure Sister chromatids: two identical halves of a chromosome Centromere: middle of a chromosome that holds the two chromatids together until they separate during cell division.

a. Why are sister chromatids important? Sister Chromatids are duplicates of a genome. When the cell divides, each cell receives a complete copy off all of the DNA Sister chromatids DNA Doubles – forming attached sister chromatids (look like an X)

Chromosome Numbers Each species has a characteristic number of chromosomes. Journal: Using evidence from the table above, does chromosome number relate to organism complexity?

b. What are the 2 types of chromosomes found in an animal cell? Sex Chromosomes: determine the gender of an organism – Male XY – Female XX Autosomes: the remaining chromosomes beyond the sex chromosomes

Homologous Chromosomes: Two copies of each autosome c. Where did each copy of the homologous Chromosomes found in your cells come from? – One from each parent – Same size and shape – Carry genes for the same trait Also called Homologues

d. What is a Karyotype? Photomicrograph of all of the chromosomes in a dividing cell

THE CELL CYCLE Sequence of growth and division in a cell In Prokaryotes: Binary Fission

The Cell Cycle In Eukaryotes: Sequence of growth and division in a cell 2 Parts: – Interphase: G1: Growth 1 – prep for DNA replication S: Synthesis – DNA replication G2: Growth 2- prep for cell division – Mitosis:

The Cell Cycle In Eukaryotes: Sequence of growth and division in a cell 2 Parts: – Interphase: Cell grows, makes proteins, and DNA is replicated in preparation for mitosis – Mitosis: The process of nuclear division that results in two daughter cells Occurs in unicellular organisms like amoeba It occurs in the addition of cells to a tissue or an organ in multicellular organisms

Mitosis: 4 phases 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase

1. Prophase Chromatin coils up into visible chromosomes Nuclear envelope disappears Centrioles migrate to opposite sides of the cell Spindle fibers form

2. Metaphase Chromosomes become attached to spindle fibers and begin to line up in the middle

3. Anaphase The sister chromatids are separated and pulled apart to opposite ends of the cell

4. Telophase The sister chromatids are at opposite ends of the cell. The nuclear envelope reappears

Cytokinesis: The division of the cell’s cytoplasm.

How is cytokinesis different between plants and animals? – In animal cells, the plasma membrane pinches in along the equator (forms a cleavage furrow) – In plant cells, a rigid cell wall is laid down along the equator (forms the cell plate)

Animal CellsPlant Cells

What are the levels of organization? Cell  Tissue  Organ  Organ System  Organism Mitosis allows for new cells to be produced. These cells will be differentiated, or specialized, during development. Remember, the basic unit of organization is still the CELL!!!

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