Chapter 1 Cells

Cell Theory

All cells comes from pre-existing cells

Cells are the basic unit of life

All organisms are made up of one or more cells

Structure of cells

How are cells categorize

Prokaryotic cells #

Eukaryotic cells #

Differs in SIZE/ SIZE OF RIBOSOMES/ COMPARTMENTALIZATION/DNA LOCATION/ DNA PRESENT IN WHAT FORM/

Reason for being so small

Surface area to volume ratio

Increase in cell radius > lower the ratio > rate of reaction greatly reduces

How are substances being transport?

Energy required

Active transport

No energy is required

Passive transport
Down a concentration gradient

Simple diffusion

Channel protein

For large molecules

Facilitated transport

Substrate induced transportation

Phagocytosis

Particles move from a higher concentration to a region of lower one

Osmosis

Water across a deferentially permeable membrane

From a region of higher water potential (Less solute) > Region of lower water potential (Many solutes)

Types of solution

Hypotonic

Isotonic

Hypertonic

Water moves out

Level of water leaves and enter the cell at the same rate

Water moves in

Why is it important

Cell membrane controls the movement in and out of the cell

Surface area greatly affect the above transportation

Small + Non-polar

Carrier protein

Polar substances

Plant cell

Animal cell

Cell wall

Protect and maintain the angular/ regular shape

Withstand high pressure due to influx of water
Cell membrane may exert great pressure on it

Chloroplsts (70s)

Bounded by a double membrane

Consists of fluid stroma
1) Provide surface area
2) Contain enzyme and chemicals
3) Contain thylakoid + Thylakoid > Granum [Absorption of light]
= necessary for the process photosynthesis

Starch granule

Special features

A kind of prokaryotic cell

Contain own DNA

Able to reproduce independently
Believe to be taken in through in-folding of cells

Plant store carbohydrate in the form of starch

Large central vacuoles

Filled with cell sap

Affect the rate of the cells

Volume

Affect the metabolism of cells

large membrane surface area allows more MATERIAL MOVELEMT

Smaller cells require LESS ENERGY for sustainability essential function

Mitochondria (70s)

Bounded by a double membrane

Inner mitochondrial membrane

Cristae

Consists semi-fluid substances known as MATRIX

Consists of enzymes and chemicals

Essential for the process RESPIRATION

Cell membrane

Provide a large surface area
1) Dissolved substances
2) Provide support when turgid

Control the movement of substances in and out of the cell

Semi-isolation for process like DNA replication

Golgi Apparatus

Flattened sac

Cristernae

1) Collection
2) Packaging
3) Modification
4) Distribution

Cytoplasm

Within plasma membrane

Jelly-filled fluid

1) Main site of chemical reaction
2) Allow substances to be transported within the cell

Endoplasmic reticulum

Extensive networks

Extends throughout the cells

Provide larger surface area for the
1) Production
2) Transporttion

Rough E.R.

Involved in the production and transportation of proteins

Smooth E.R.

1) Production of MEMBRANE PHOSPHOLIPID + Cellular lipid
2) Production of sex hormones

Male > Testosterone
Female > Oestrogen
3)Transportation of lipid-based compound

Centrosome

Contain a pair of centroiles at right angle

Help guide chromosomes / sister chromatids to opposite poles for the separation of cells

Vacuoles

Membrane bounded sacs with dissolves substances and water

Transparent under light microscope

How cells produce new cells?

Interphase

Smallest as it can ever be

DNA replication > Formation of homologous pairs

Extracellular Matrix

Composition
1) Glycoprotein
2) Collagen fiber

Function

1) Enable coordination of cell actions within tissue

2) Strength cell membrane

3) Allow alternating of gene expression

4) Allow cell-to-cell communication/ interaction

5) Allow attachment between adjacent cells

Prokaryotic cell

Pilli

Hair-like growth for
1) Joining of bacterial cells
2) Prepare the transferal of DNA

Flagella

Hair like growth for mobility of cell
(E.g. Sperm)

Nucleus

Features
1) Bounded by a double membrane
2) Spherical in shape

Contains DNA > All information that is essential for the exists of cells

Increase in no. of organelles

micro-tubules has began it's formation

Begins to condense

Still invisible under light microscope

Prophase

1) Chromatin shorten and thicken > Visible
2) Nuclear membrane extinguishes
3) Spindle fibers has formed at the end of peophase
4) Each centromere of chromosomes contain a region called kinetochore
5) After the formation of spindle fiber > Attachment with spindle
6) The chromosomes move slightly towards opposite poles

Metaphase

1) By the action of micortubules > movement of spindle fiber
2) Chromosomes lie along the equator of the cell
3) Centrosome is now one opposite poles

Anaphase

1) Spindle fibers shorten and thicken
2) Sister chromatids move to opposite poles

Telophase

1) Elongation of chromosomes
2) Disappearance of nucleoli > Chromosomes uncoiled to become chromatins
3) Disappearance of spindle fibers
4) Cell is elongated and are ready for cytokineasis

Cytokinesis

Animal cells

Plant cells

Building up of cell plate > Made of spindle fibers Ftz

Separated by contractile ring forming cleavage furrow > Seperates

Example - Sodium-potassium pump

1) Binding of three intracellular sodium ions
2) Binding action causes phosphorylation by ATP.

One phosphate is lost during the process > Transferal of ATP to ADP
3) Phosphorylation - causes the change in shape
4) Causes the expelling of sodium ions to the exterior
5)Two extracellular potassium than bind to the the exterior side
6)The binding action causes the release of phosphate group
7) Resume of original shape
8) Causes the release of potassium ions into the intracellular space

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