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Survey A&P CELL FUNCTION Instructor Terry Wiseth CELL DIVISION the process of cell division is essential to the growth and development of all organisms growth and tissue repair are common occurrences abnormal cell division is commonly called cancer 2 DNA REPLICATION parent cells must provide daughter cells with hereditary instructions and enough cytoplasmic machinery to start up with their own operation DNA REPLICATION Cells divide DNA by: 1) Mitosis Occurs in somatic cells Most of the cells of the body 2) Meiosis Occurs in germ cells Sperm and egg cells 4 CHROMOSOMES Chromosomes are the genetic material found inside the nucleus of the cell 5 CHROMOSOMES Consist of condensed DNA and proteins DNA controls protein synthesis Controls the appearance of characters and metabolic activities of an organism 6 CHROMOSOME DNA loops 7 CHROMOSOMES Each species has a fixed number of chromosomes in the nucleus of each of its cells Chromosomes always exist in pairs in the body cells 8 SOMATIC CELLS somatic cells in each species of organism will have the same number of chromosomes specific to that species ex: humans = 46 gorillas = 48 pea plant = 14 9 CELL CYCLE Mitosis M Gap phase 1 G1 Synthesis phase S Gap phase 2 G2 10 CELL CYCLE M (mitosis) nuclear division cytoplasmic division G1 (gap 1) interval before the onset of DNA replication 11 CELL CYCLE S (synthesis) replication of DNA G2 (gap 2) interval between completion of DNA replication and the onset of mitosis 12 INTERPHASE usually the longest phase of the cell cycle 13 INTERPHASE consists of the G1,S, and G2 phases of the cell cycle 14 INTERPHASE 1) the cell increases in mass 2) chromosomes cannot be seen 3) chromosomes are duplicated 15 INTERPHASE 16 STAGES OF MITOSIS Prophase Interphase 19 hrs Mitosis 1 hr Metaphase Anaphase Telophase 17 PROPHASE 1) chromosomes start condensing chromatids twist and fold on one another 2) spindle fibers begin to form 18 PROPHASE 3) centrioles are duplicated and begin to migrate to opposite poles centrioles later give rise to cilia and flagella 19 PROPHASE 20 PROPHASE 21 METAPHASE 1) nuclear membrane disappears 2) spindle fibers attach to chromosome centromeres 22 METAPHASE 3) spindle fibers from opposite poles “pull” on the chromosomes orientating them at the equator 4) chromosomes become aligned at the cell equator 23 METAPHASE 24 METAPHASE 25 ANAPHASE 1) the two sister chromatids of each chromosome are separated 2) chromatids move to opposite poles 26 ANAPHASE 27 TELOPHASE 1) the daughter chromosomes arrive at opposite poles 2) chromosomes begin to unwind and decondense to a threadlike DNA molecule 28 TELOPHASE 3) nuclear membranes form, enclosing the DNA 4) each new daughter cell has the same number of chromosomes as the parent cell 29 TELOPHASE 30 INTERPHASE 31 DIVISION OF THE CYTOPLASM the cytoplasm divides during Telophase cytokinesis- cytoplasmic division 32 DIVISION OF THE CYTOPLASM animal cells “pinch in two” by a process called cleavage 33 DIVISION OF THE CYTOPLASM Abnormal cell division at this point can lead to physical deformities 34 METABOLISM Metabolism - the capacity to acquire energy and use it to build, store, break apart and eliminate substances in controlled ways Energy - the capacity to make things happen 35 METABOLISM cells secure, use and lose energy cells cannot create energy cells must get energy from somewhere else 36 METABOLISM Most energy available for energy conversion is stored in covalent bonds glucose, starch, glycogen and fatty acids are rich in covalent bonds When molecules are broken apart there is a controlled release of energy which is available to make things happen 37 METABOLISM 38 CHEMICAL REACTIONS Many reactions in the cell result in the production of ATP or the use of ATP ex: Cellular respiration C6H12O6 + O2 CO2 + H2O 39 REACTANTS & PRODUCTS reactants products products or reactants 40 METABOLIC PATHWAYS Orderly sequence of reactions with specific enzymes acting at each step 41 REACTION SEQUENCES If the sequence is interrupted the pathway does not continue and by-products begin to accumulate 42 BIOSYNTHETIC PATHWAY Biosynthetic (anabolism) - small molecules are assembled into large molecules of higher energy content Requires the input or use of ATP ex: amino acids proteins fatty acids lipids glucose starch 43 BIODEGRADATIVE PATHWAY Biodegradative (catabolism) - large molecules are broken down to smaller molecules of lower energy content ex: starch glucose protein amino acids lipids fatty acids 44 ENZYMES PROPERTIES Able to speed up reactions (million fold) described as catalytic molecules 45 EFFECTS OF TEMPERATURE ON ENZYME ACTIVITY Enzymes function best within a certain temperature range Enzymes lose their 3-dimensional shape when exposed to high heat ex: human cell death - 112 degrees F ex: Siamese cat – coloring pattern 46 EFFECTS OF TEMPERATURE ON ENZYME ACTIVITY Siamese cat-- ears and paws are the darkest part of the body Heat sensitive enzyme is less active in warmer regions of the body Enzyme influences higher melanin production 47 EFFECTS OF pH ON ENZYME ACTIVITY Enzymes function best within a certain pH range most function best at pH=7 (neutral) exception: pepsin (a stomach cell enzyme) works best at low pH 48 ATP is the energy currency ATP of the cell The breakdown of organic molecules by the cell releases energy which is converted to units of ATP energy ATP energy is then utilized by the cell to perform a multitude of cell functions 49 PATHWAYS LEADING TO ATP FORMATION 1) Aerobic respiration 2) Anaerobic respiration O2 Glucose CO2 + H2O + ATP 50 PATHWAYS LEADING TO ATP FORMATION 1) Aerobic respiration 2) Anaerobic respiration Glucose Pyruvate + ATP 51 PATHWAYS LEADING TO ATP FORMATION 1) Aerobic respiration 2) Anaerobic respiration O2 Glucose CO2 + H2O + ATP Pyruvate + ATP 52 PATHWAYS LEADING TO ATP FORMATION 1) Aerobic respiration requires oxygen most cells are able to perform 53 PATHWAYS LEADING TO ATP FORMATION 2) Anaerobic respiration does not require oxygen 54 PATHWAYS LEADING TO ATP FORMATION The amount of ATP energy produced by respiration varies Aerobic respiration yields 36 ATP from 1 glucose Anaerobic respiration yields only 2 ATP from 1 glucose 55 AEROBIC RESPIRATION C6H12O6 + 6O2 6CO2 + 6H2O + ATP energy 56 ALTERNATIVE ENERGY SOURCES IN THE HUMAN BODY 1) Carbohydrates 2) Fats 3) Proteins 57 ENERGY SOURCES very little energy is stored as glucose by the body Fats-------------------- 78% Proteins-------------- 21% Carbohydrates---- 1% 58 END CELL FUNCTIONS 59
