Basic Cell Structure

Cells Basic building blocks of life Understanding of cell structure is critical to the study of biotechnology

Cell Smallest living unit of an organism Grow, reproduce, use energy, adapt, respond to their environment

Cell Many cannot be seen with the naked eye A cell may be an entire organism or it may be one of billions of cells that make up the organism

Cells Divided and classified in many ways One common classification method is the presence or absence of a cell necleus

Nucleus Relatively large structure with a cell Directs cell activities Some simple single celled organisms lack a nucleus

Common structures Organelles – smaller parts of the cell with specific funtions Cell membrane – acts as a gatekeeper

Cell membrane Controls what enters and leaves the cell Plants, algae and bacteria typically have a tough outer structure known as a cell wall

Cell wall Provides additional structure and protects the cell from pressure caused by movement of water Animal cells do not have walls

Cytoplasm Organelles are surrounded by a jelly like substance Primary component is water

Nucleus Largest and most identifiable part of the cell

Other organelles Ribosomes Mitochondria Golgi bodies Endoplasmic reticulum

Other organelles Lysosomes Vacuoles Chloroplasts in plants

Nucleus Brain of the cell Site of much of the manipulation done in biotechnology

Nucleus Controls activity of the cell Round or oval structure Typically found in the middle of the cell Appears darker than surrounding material

Nucleus Surrounded by a membrane that controls passage of materials in and out of the area

Nucleus Contains DNA DNA is located on chromosomes Most organisms are diploid – have tow chromosomes for each trait

Diploid Humans – 23 pair Goldfish – 90 chrms, 45 pair

Cytoplasmic Organelles Organelles are required for proper cell function Ribosome – make proteins for cellular use and communication May be attached to endoplasmic reticulum

Endoplasmic reticulum Layered membraneous Make and transport proteins

Vacuole Large organelle, without specific shape Store waste or raw materials used in synthesis of proteins

Golgi Bodies Golgi apparatus Similar to endo. Ret. Look like a thick elastic band that has been folded several times

Golgi Bodies Adds modifications to unfinished proteins Makes lysosomes

Lysosome Small round Store enzymes that break down food into chemical compounds Destroy cell organelles and the cell itself

Mitochondria Energy factories Rod shaped Change food into molecules that can be used for energy

Mitochondria Contain DNA Can replicate themselves

Chlorplast Found in plants and some other organisms Contain chlorophyll

Cellular processes Respiration Osmosis Diffusion Photosynthesis

Respiration Cells break down carbohydrates and other molecules to produce energy Oxidation of glucose is one of most common forms

Respiration Breaking down of sugar into water, carbon dioxide, and energy Energy is used to do the work of the cell

Osmosis & Diffusion Transport of raw materials, wastes, and synthesized materials out of the cell

Diffusion Movement of molecules, especially gases and liquids from areas of high concentration to areas of low concentration

Osmosis Specific type of diffusion Movement of water through a membrane from areas of high concentration to areas of low concentration

Equilibrium Diffusion and osmosis happen to enable a cell to reach equilibrium

Cellular reproduction Three ways Fission Mitosis Meiosis

Fission Prokaryotes Cell grows larger and makes a second copy of its DNA At some point the cell membrane divides the cell by the growth of a transverse septum

Fission Two new cells are formed as the division grows inward from either side of the cell Two cells now called “daughter cells” Sometimes known as “binary fission”

Mitosis Eukaryotes Requires 6 stages Interphase, prophase, metaphase, anaphase, telophase, cytokinesis

Mitosis Creates cells that are identical to the original cell. Have the entire compliment of chromosomes existing in pairs - diploid

Meiosis Division of sex cells Stages of Meiosis I: Interphase I, prophase I, metaphase I, anaphase I, telophase I, cytokinesis I

Meiosis Meiosis II Interphase II, prophase II, metaphase II, anaphase II, telophase II, cytokinesis II

Meiosis Each cell receives one chromosome from each pair randomly Resulting cells have half the normal number of Chromosomes - haploid