2.1 The Importance of Cell Division

Transcription

1 2.1 The Importance of Cell Division

2 Functions of cell division Growth Repair Reproduction

3 Growth All organisms begin as a single cell. Cell divisions will increase as an organism s size increases. There are limits to the size of a cell so they will need to divide. Cells will specialize and form tissues and organs.

4 Repair Old cells and dead cells need to be replaced. Some cells need to be replaced more often than others.

5 Reproduction Unicellular organisms such as bacteria use cell division for reproduction. This results in two identical cells being produced. It also allows for rapid population growth. Some multicellular organisms use cells division for reproduction (mushrooms).

6 Assignment P. 38#2-8, Plant and Animal Cell Diagrams Venn Diagram

7 2.2 Cells Structures Involved in Cell Division

8 Nucleus Directs all cells activities, including cell division

9 Nuclear Membrane Allows material to pass into and out of nucleus. It surrounds the nucleus.

10 Chromosomes Made of DNA (deoxyribonucleic acid) and protein. It looks like a twisted ladder.

11 Nucleolus Site for production and assembly of ribosomes

12 Ribosomes Tiny organelles in the cytoplasm which make protein. They are either free or attached to the endoplasmic reticulum.

13 Cytoplasm Located inside the cell membrane. Most of the cell s activities happen here. Nutrients are absorbed, transported and processed here.

14 Centrioles These are contained in the cytoplasm. They are made of special microtubles. These are found mainly in animal cells and are active during cell division.

15 Assignment P. 41 #1-12, 14, 16-17

16 2.3 DNA to Protein

17 DNA Deoxyribonucleic acid (DNA) is special because it has the ability to replicate Its building block are called nucleotides

18 Nucleotides A nucleotide is made of a sugar, a phosphate and a nitrogenous base.

19 There are 4 types of nitrogenous bases Adenine, thymine, cytosine, guanine Adenine pairs with thymine Cytosine pairs with guanine YouTube - DNA Structure

20 DNA codes for protein building. Words are created from 3 nitrogenous base s Each 3 letter word codes for an amino acid Codon Chart

21 Amino acids are the building blocks for proteins A gene is a short section of DNA which codes for a protein

22 Protein Synthesis DNA segment splits and makes a molecule of RNA using half the DNA strand RNA moves into the cytoplasm Ribosomes read the code and assembles amino acids into proteins DNA to Protein Animation

23 RNA Ribonucleic acid is a similar molecule to DNA, but it does not replicate and it has only one strand

24 DNA Replication DNA molecules will separate between base pairs Each side acts as a template for free nucleotides to join strand

25 A trait is a version of a characteristic Example: Blue eyes is a trait. Eye colour is a characteristic.

26 A genome is all an organism s genes.

27 Assignment P. 47 #1, 5, 7-9, 12-15

28 2.4 The Cell Cycle - Mitosis

29 Interphase 90% of the cell cycle. Copies of DNA and organelles are made. Copies of DNA are known as sister chromatids. Cells are growing and working.

30 Prophase Sister chromatids are joined at the centre, they are shortened and thickened. The nucleolus is no longer visible. The nuclear membrane breaks down and chromatids spread out. Centrioles move to opposite sides of the cell and form spindle fibres.

31 Metaphase Spindle fibres are completely formed. Sister chromatids attach to spindle fibres and line up along the middle of the cell.

32 Anaphase Sister chromatids are pulled apart and move to opposite ends of the cell. Sister chromatids are now known as chromosomes.

33 Telophase Two nuclear membranes begin to appear. Spindle fibres disappear. Chromosomes lengthen and get thinner. Nucleoli reappear.

34 Daughter Cells Identical to parent cells. Interphase begins.

35 Mitosis and Cytokinesis Comparison Mitosis is the division of a cell s nuclear material Cytokinesis is the division of the non-nuclear material (ie ribosomes, chloroplasts)

36 Assignment P. 52#4-6, 8, 10, 13, 15-17

37 2.5 Changes to Cell s DNA

38 Mutation A change to a cell s DNA. It may be beneficial, neutral or harmful.

39 Cancer Cells which divide rapidly or uncontrollably. This mutation is passed to daughter cells.

40 Tumors An accumulation of abnormal masses. It may be benign or malignant.

41 Benign These cells stay in place and do not interfere with the functioning of surrounding tissues or organs.

42 Malignant These cells invade surrounding tissues and interfere with normal functioning of tissues and organs.

43 Metastasis The spreading of cancer cells away from their original location.

44 Causes Carcinogens (substances which cause cancer) Your own genetic make up.

45 Treatment Surgery Radiation Chemotherapy Or combination The outcome is best if cancer is caught early.

46 Assignment P. 56 #2-3, 5, 10-13, 15

47 2.6 Cell Division and Asexual Reproduction

48 Asexual Reproduction Requires only one parent All offspring are identical (to parent and each other) A single organism can produce a large amount of offspring

49 Binary Fission Single celled organisms Offspring smaller than parent Rapid growth can occur (population doubles every 20 minutes)

50 Budding Offspring begins as a small growth on the parent Organism continues to grow and breaks off parent cell Examples- yeast, hydra

51 Vegetative Reproduction A form of plant reproduction Several methods including runners, shoots, cuttings, bulbs and tubers

52 Fragmentation A small part of an organism breaks off and grows into a new organism Requires regeneration to occur Flat worms, sea stars

53 Regeneration Regrowing a body part Not a form of reproduction

54 Spore Formation Cells with walls, similar to seeds Produced by cell division Genetically identical to parent Organisms may also produce sexually

55 Assignment P. 60#1-4, 6, 11-14, 16, 17

56 Review Assignment P. 70#1-21