Human Biology Instructor Terry Wiseth CELLFUNCTION

2 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

DNA REPLICATION parent cells must provide daughter cells with hereditary instructions and enough cytoplasmic machinery to start up with their own operation

4 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

5 CHROMOSOMES Chromosomes are the genetic material found inside the nucleus of the cell

6 CHROMOSOMES Consist of condensed DNA and proteins  DNA controls protein synthesis  Controls the appearance of characters and metabolic activities of an organism

7 CHROMOSOME DNA loops

8 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

9 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

10 CELL CYCLE Mitosis M Gap phase 1 G 1 Synthesis phase S Gap phase 2 G 2

11 CELL CYCLE M (mitosis) M (mitosis)  nuclear division  cytoplasmic division G 1 (gap 1)  interval before the onset of DNA replication

12 CELL CYCLE S (synthesis)  replication of DNA G 2 (gap 2)  interval between completion of DNA replication and the onset of mitosis

13 INTERPHASE usually the longest phase of the cell cycle

14 INTERPHASE consists of the G1,S, and G2 phases of the cell cycle

15 INTERPHASE  1) the cell increases in mass  2) chromosomes cannot be seen  3) chromosomes are duplicated

16 INTERPHASE

17 STAGES OF MITOSIS Prophase Metaphase Anaphase Telophase Interphase 19 hrsMitosis 1 hr

18 PROPHASE 1) chromosomes start condensing  chromatids twist and fold on one another 2) spindle fibers begin to form

19 PROPHASE 3) centrioles are duplicated and begin to migrate to opposite poles  centrioles later give rise to cilia and flagella

20 PROPHASE

21 PROPHASE

22 METAPHASE 1) nuclear membrane disappears 2) spindle fibers attach to chromosome centromeres

23 METAPHASE 3) spindle fibers from opposite poles “pull” on the chromosomes orientating them at the equator 4) chromosomes become aligned at the cell equator

24 METAPHASE

25 METAPHASE

26 ANAPHASE 1) the two sister chromatids of each chromosome are separated 2) chromatids move to opposite poles

27 ANAPHASE

28 TELOPHASE 1) the daughter chromosomes arrive at opposite poles 2) chromosomes begin to unwind and decondense to a threadlike DNA molecule

29 TELOPHASE 3) nuclear membranes form, enclosing the DNA 4) each new daughter cell has the same number of chromosomes as the parent cell

30 TELOPHASE

31 INTERPHASE

32 DIVISION OF THE CYTOPLASM the cytoplasm divides during Telophase cytokinesis- cytoplasmic division

33 DIVISION OF THE CYTOPLASM animal cells “pinch in two” by a process called cleavage

34 DIVISION OF THE CYTOPLASM Abnormal cell division at this point can lead to physical deformities

35 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

36 METABOLISM  cells secure, use and lose energy  cells cannot create energy  cells must get energy from somewhere else

37 METABOLISM covalent bonds  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

38 METABOLISM

39 CHEMICAL REACTIONS  Many reactions in the cell result in the production of ATP or the use of ATP C 6 H 12 O 6 + O 2 CO 2 + H 2 O  ex: Cellular respiration C 6 H 12 O 6 + O 2 CO 2 + H 2 O

40 REACTANTS & PRODUCTS  reactants products or  products reactants

41 METABOLIC PATHWAYS  Orderly sequence of reactions with specific enzymes acting at each step

42 REACTION SEQUENCES  If the sequence is interrupted the pathway does not continue and by-products begin to accumulate

43 BIOSYNTHETIC PATHWAY  Biosynthetic (anabolism)  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

44 BIODEGRADATIVE PATHWAY  Biodegradative (catabolism)  Biodegradative (catabolism) - large molecules are broken down to smaller molecules of lower energy content  ex: starchglucose  proteinamino acids  lipidsfatty acids

45 ENZYMES PROPERTIES speed up reactions  Able to speed up reactions (million fold)  described as catalytic molecules

46 temperature range  Enzymes function best within a certain temperature range  Enzymes lose their 3-dimensional shape when exposed to high heat  ex: human cell death degrees F  ex: Siamese cat – coloring pattern EFFECTS OF TEMPERATURE ON ENZYME ACTIVITY

47  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 EFFECTS OF TEMPERATURE ON ENZYME ACTIVITY

48 EFFECTS OF pH ON ENZYME ACTIVITY pH range  Enzymes function best within a certain pH range  most function best at pH=7 (neutral) pepsin  exception: pepsin (a stomach cell enzyme) works best at low pH

49 ATP ATP is the energy currency 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

50 PATHWAYS LEADING TO ATP FORMATION 1) Aerobic respiration 1) Aerobic respiration 2) Anaerobic respiration Glucose CO 2 + H 2 O O2O2 + ATP

51 PATHWAYS LEADING TO ATP FORMATION 1) Aerobic respiration 2) Anaerobic respiration 2) Anaerobic respiration Glucose Pyruvate+ ATP

52 PATHWAYS LEADING TO ATP FORMATION 1) Aerobic respiration 2) Anaerobic respiration Glucose Pyruvate CO 2 + H 2 O O2O2 + ATP

53 PATHWAYS LEADING TO ATP FORMATION 1) Aerobic respiration  requires oxygen  most cells are able to perform

54 PATHWAYS LEADING TO ATP FORMATION 2) Anaerobic respiration  does not require oxygen

55 PATHWAYS LEADING TO ATP FORMATION The amount of ATP energy produced by respiration varies  Aerobic respiration 36 ATP  yields 36 ATP from 1 glucose  Anaerobic respiration 2 ATP  Anaerobic respiration yields only 2 ATP from 1 glucose

56 AEROBIC RESPIRATION C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + ATP energy

57 ALTERNATIVE ENERGY SOURCES IN THE HUMAN BODY 1) Carbohydrates 2) Fats 3) Proteins

58 ENERGY SOURCES very little energy is stored as glucose by the body  Fats %  Proteins %  Carbohydrates---- 1%

59 END CELL FUNCTIONS