2.1 the importance of cell division

2.1 The Importance of Cell Division

Functions of cell division

● Growth ● Repair ● Reproduction

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.

Repair

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

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).

Assignment

● P. 38#2-8, 10-14 ● Plant and Animal Cell Diagrams ● Venn Diagram

2.2 Cells Structures Involved in Cell Division

Nucleus

● Directs all cells activities, including cell division

Nuclear Membrane

● Allows material to pass into and out of nucleus. It surrounds the nucleus.

Chromosomes

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

Nucleolus

● Site for production and assembly of ribosomes

Ribosomes

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

Cytoplasm

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

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.

Assignment

● P. 41 #1-12, 14, 16-17

2.3 DNA to Protein

DNA

● Deoxyribonucleic acid (DNA) is special because it has the ability to replicate

● Its building block are called nucleotides

Nucleotides

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

There are 4 types of nitrogenous bases

● Adenine, thymine, cytosine, guanine

● Adenine pairs with thymine

● Cytosine pairs with guanine

● YouTube - DNA Structure

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

● Amino acids are the building blocks for proteins

● A gene is a short section of DNA which codes for a protein

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

RNA

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

DNA Replication

● DNA molecules will separate between base pairs ● Each side acts as a template for free nucleotides

to join strand

● A trait is a version of a characteristic

Example: Blue eyes is a trait. Eye colour is a characteristic.

● A genome is all an organism’s genes.

Assignment

● P. 47 #1, 5, 7-9, 12-15

2.4 The Cell Cycle - Mitosis

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.

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.

Metaphase

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

Anaphase

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

Telophase

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

Daughter Cells

● Identical to parent cells. Interphase begins.

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)

Assignment

● P. 52#4-6, 8, 10, 13, 15-17

2.5 Changes to Cell’s DNA

Mutation

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

Cancer

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

Tumors

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

Benign

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

Malignant

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

Metastasis

● The spreading of cancer cells away from their original location.

Causes

● Carcinogens (substances which cause cancer)

● Your own genetic make up.

Treatment

● Surgery ● Radiation ● Chemotherapy ● Or combination

● The outcome is best if cancer is caught early.

Assignment

● P. 56 #2-3, 5, 10-13, 15

2.6 Cell Division and Asexual Reproduction

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

Binary Fission

● Single celled organisms

● Offspring smaller than parent

● Rapid growth can occur (population doubles every 20 minutes)

Budding

● Offspring begins as a small growth on the parent

● Organism continues to grow and breaks off parent cell

● Examples- yeast, hydra

Vegetative Reproduction

● A form of plant reproduction

● Several methods including runners, shoots, cuttings, bulbs and tubers

Fragmentation

● A small part of an organism breaks off and grows into a new organism

● Requires regeneration to occur

● Flat worms, sea stars

Regeneration

● Regrowing a body part ● Not a form of reproduction

Spore Formation

● Cells with walls, similar to seeds

● Produced by cell division

● Genetically identical to parent

● Organisms may also produce sexually

Assignment

● P. 60#1-4, 6, 11-14, 16, 17

Review Assignment

● P. 70#1-21