Resumen Topic 2 Biologia Ib

Resumen Topic 2
Biology SL IB
2012

2.1 CELL THEORY

2.1.1 OUTLINE the cell theory

* Cells are the smallest unit of LIFE

* All living things consist of cells

* All cells come from other cells that existed before

2.1.2 DISCUSS evidence for this theory

* Cells that are separated drom an organism can survive on its own for a time, smaller things cannot, this showsthat cells are the smallest unit of LIFE

* Almost all living things have cells, except fungi, muscle and bones.

2.1.3 STATE that unicelular organisms carry out all functions of life

1. Nutrition: Obtain food, provide energy and materials needed for growth
2. Metabolism: All chemical reactions inside cells.
3. Growth: An irreversible increase of size
4. Sensitivity: Topercieve and respond to changes in the enviroment.
5. Homeostasis: Keeping the conditions inside the organism constant.
6. Reproduction: To produce an offspring either sexually or asexually

Examples of Unicellular organisms are:

a) Yeast
b) Amoeba
c) Sponge
d) Viruses

2.1.4 Compare sizes of molecules, cell membrane thickness, viruses, bacteria,organelles and cells using the appropriate unit.

Meters (m) x100 Centimetres (cm) x10 Millimetres (mm) x1000 Micrometres (Mm) x1000 Nanometres (nm)

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Eukaryotic cells: 10 Mm – 100 Mm
Organelles: 1 Mm – Mm
Bacteria: 1Mm
Viruses: 100nm
Cell Membrane Thickness: 10nm
Molecules: 1nm
Atoms: 0.1nm

2.1.5 Calculate magnificationSize of Image
Magnification= ------------------------------
Actual Size of Specimen

2.1.6 Explain the importance of surface area and volume

* Surface area determines the rate of Exchange of substances across the cell membrane and heat loss
* Volume determines the amount of substances used during metabolism
* TheSurface Area: Volume ratio decreases with the increase of the cell size

2.1.8 Explain that cells in multicellular organisms differentiate to carry out
Specialized functions by expressing some of their genes but not others

Different cells are in charge of different things; this is why cells are specialized for their job. A cell determines what it will do with factors like the position ofcells, chemicals, hormones and cell-to-cell signals.

A group of differentiated cells is called a tissue

2.1.9 State that stem cells can divide and have the ability to differentiate along
Different pathways

Stem cells can self-renew and have the ability to become any cell they want. Humans start as stem cells.
2.1.10 Outline one therapeutic use of stem cells.

As stem cells can becomeany type of cell, when a patient cells aren’t
Working well, stem cells are placed there to help the cells work properly

2.2 Prokaryotic cells

2.2.1 Draw and label a Prokaryotic Cell

2.2.2 Functions of each structures

Cell Wall:
a) Protect the cell
b) Maintain Cell’s shape
c) Prevents cell from bursting
Plasma Membrane:
a) Control what goes in and out of cellb) Pumps substances by active transport
Cytoplasm
a) Contains ribosomes
b) It is water with dissolved substances
c) It carries the chemical reactions of metabolism
Ribosomes:
a) Synthesize Proteins
Nucleoid:
a) Region of cytoplasm that contains genetic material
Pili:
a) Used for cell adhesion
Flagella:
a) Using energy, it moves the cell from an area to another.2.2.4 State that prokaryotic cells divide by binary fusion

1. Cell Elongates and DNA is replicated
2. Cell wall and plasma membrane begin to divide
3. Cross-wall forms completely around divided DNA
4. Cells separate

2.3 Eukaryotic cells

2.3.1 Draw and label a Eukaryotic Cell

2.3.2 Functions of each structure

Nucleus: Stores almost all genetic...