DMI 261 DMI 261 Radiation Biology Radiation Biology andandProtectionProtection

Unit 6Unit 6The Human CellThe Human Cell

Cell Biology ReviewCell Biology Review

Principle Cell Principle Cell MoleculesMolecules WaterWater 80%80% ProteinsProteins 15%15% LipidsLipids 2% 2% CarbohydratesCarbohydrates 1% 1% Nucleic AcidsNucleic Acids 1% 1%

Cell’s Chemical Cell’s Chemical CompositionComposition

Nucleic AcidsNucleic Acids RNARNA DNA DNA

– Double helixDouble helix– Sugar-phosphate Sugar-phosphate

chains chains – Nitrogenous Nitrogenous

basesbases

Nitrogenous BasesNitrogenous Bases Purines – Adenine and GuaninePurines – Adenine and Guanine Pyrimidines – Thymine and Pyrimidines – Thymine and

CytosineCytosine

– adenine only bonds with guanineadenine only bonds with guanine– thymine only bonds with cytosinethymine only bonds with cytosine– Hydrogen bondsHydrogen bonds hold the bases hold the bases

togethertogether

Cell StructureCell Structure

Cell StructureCell Structure Cell membraneCell membrane

– BarricadeBarricade– Controls passage of water and other Controls passage of water and other

materials in and out of the cell.materials in and out of the cell.

CytoplasmCytoplasm– Protoplasm that exists outside of the Protoplasm that exists outside of the

nucleus.nucleus.

OrganellesOrganelles Endoplasmic Endoplasmic

ReticulumReticulum– Transportation Transportation

system for food system for food and communication and communication with outside with outside environmentenvironment

– Rough have Rough have ribosomesribosomes

– Smooth do notSmooth do not

OrganellesOrganelles Golgi ApparatusGolgi Apparatus

– Concentrates, Concentrates, packages and packages and transports transports enzymes and enzymes and hormones hormones through the cell through the cell membranemembrane

OrganellesOrganelles MitochondriaMitochondria

– Power house of Power house of the cellthe cell

– Produces energy Produces energy for cell activity by for cell activity by breaking down breaking down nutrientsnutrients

OrganellesOrganelles LysosomesLysosomes

– Garbage disposalsGarbage disposals– Break down large Break down large

molecules that molecules that enter the cellenter the cell

– Contain digestive Contain digestive enzymes that can enzymes that can destroy a cell if its destroy a cell if its membrane membrane rupturesruptures

OrganellesOrganelles RibosomesRibosomes

– Protein factoriesProtein factories– Make proteins as Make proteins as

instructed by instructed by mRNAmRNA

OrganellesOrganelles CentrosomesCentrosomes

– Contain centrioles Contain centrioles which help form which help form mitotic spindlesmitotic spindles

OrganellesOrganelles NulceusNulceus

– Heart of the cellHeart of the cell– Contains DNA, Contains DNA,

nucleolus (RNA), nucleolus (RNA), controls cell controls cell division and all division and all other cellular other cellular activityactivity

Cell DivisionCell Division Multiplication process by which one Multiplication process by which one

cell forms two or more cellscell forms two or more cells

MitosisMitosis Process by which Process by which

somaticsomatic cells cells dividedivide

InterphaseInterphase Period of cell Period of cell

growth that growth that occurs before occurs before mitosis.mitosis.

DNA replication DNA replication occurs here.occurs here.

Cell CycleCell CycleG1, S, and G2 = parts of interphase that lead up to G1, S, and G2 = parts of interphase that lead up to

mitosismitosis

Stages of MitosisStages of Mitosis

MeiosisMeiosis Method by which germ cells Method by which germ cells

(reproductive) divide in sexually (reproductive) divide in sexually reproducing plants and animals.reproducing plants and animals.

Only ½ of the chromosomes are Only ½ of the chromosomes are produced.produced.

Process of Process of reduction divisionreduction division where the cell divides twice but where the cell divides twice but DNA is replicated only once.DNA is replicated only once.

MeiosisMeiosis

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