DMI 261 Radiation Biology and Protection Unit 6 The Human Cell Cell Biology Review

Principle Cell Molecules Water80% Water80% Proteins15% Proteins15% Lipids 2% Lipids 2% Carbohydrates 1% Carbohydrates 1% Nucleic Acids 1% Nucleic Acids 1%

Cell’s Chemical Composition

Nucleic Acids RNA RNA DNA DNA –Double helix –Sugar-phosphate chains –Nitrogenous bases

Nitrogenous Bases Purines – Adenine and Guanine Purines – Adenine and Guanine Pyrimidines – Thymine and Cytosine Pyrimidines – Thymine and Cytosine –adenine only bonds with guanine –thymine only bonds with cytosine –Hydrogen bonds hold the bases together

Cell Structure

Cell membrane Cell membrane –Barricade –Controls passage of water and other materials in and out of the cell. Cytoplasm Cytoplasm –Protoplasm that exists outside of the nucleus.

Organelles Endoplasmic Reticulum Endoplasmic Reticulum –Transportation system for food and communication with outside environment –Rough have ribosomes –Smooth do not

Organelles Golgi Apparatus Golgi Apparatus –Concentrates, packages and transports enzymes and hormones through the cell membrane

Organelles Mitochondria Mitochondria –Power house of the cell –Produces energy for cell activity by breaking down nutrients

Organelles Lysosomes Lysosomes –Garbage disposals –Break down large molecules that enter the cell –Contain digestive enzymes that can destroy a cell if its membrane ruptures

Organelles Ribosomes Ribosomes –Protein factories –Make proteins as instructed by mRNA

Organelles Centrosomes Centrosomes –Contain centrioles which help form mitotic spindles

Organelles Nulceus Nulceus –Heart of the cell –Contains DNA, nucleolus (RNA), controls cell division and all other cellular activity

Cell Division Multiplication process by which one cell forms two or more cells Multiplication process by which one cell forms two or more cells

Mitosis Process by which somatic cells divide Process by which somatic cells divide

Interphase Period of cell growth that occurs before mitosis. Period of cell growth that occurs before mitosis. DNA replication occurs here. DNA replication occurs here.

Cell Cycle G1, S, and G2 = parts of interphase that lead up to mitosis

Stages of Mitosis

Meiosis Method by which germ cells (reproductive) divide in sexually reproducing plants and animals. Method by which germ cells (reproductive) divide in sexually reproducing plants and animals. Only ½ of the chromosomes are produced. Only ½ of the chromosomes are produced. Process of reduction division where the cell divides twice but DNA is replicated only once. Process of reduction division where the cell divides twice but DNA is replicated only once.

Meiosis

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