Cell Biology: The Cell, its Structure and History

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The Cell: Its History, Structure, & Forms Earshad B. Banjal Instructor University of Mindanao

Transcript of Cell Biology: The Cell, its Structure and History

Page 1: Cell Biology: The Cell, its Structure and History

The Cell:Its History, Structure, & FormsEarshad B. Banjal

Instructor

University of Mindanao

Page 2: Cell Biology: The Cell, its Structure and History

Cell BiologyThe Invention of the Microscope

A microscope produces an enlarged image of something very small.

In the 1600s, a Dutch lens maker, Zacharias Jansen, invented one of the microscope’s earliest prototypes.

Today, microscopes are available in varieties:

Compound Microscopes

Stereomicroscopes

Electron Microscopes

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Cell Biology

The Discovery of the CellIn 1665, Robert Hooke used anearly compound microscope tolook at a nonliving thin slice ofcork, a plant material; termedthem as cells.

In Holland, Anton van Leeuwenhoek used a single-lens microscope to observe pond water and other things; termed them as animalcules.

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Cell Biology

The Discovery of the Cell

Felix Dujardin termed allsubstances found inside thecell as sarcode.

Later, Jan EvangelistaPurkinje, called it asprotoplasm.

Robert Brown discovered thenucleus.

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Prokaryotes & Eukaryotes

ProkaryotesDo not contain a nucleus

Do not have membrane-bound organelles

Small in size

Examples are Bacteria and Archaea

EukaryotesCells contain a nucleus

Have membrane-bound organelles

Mostly larger than a prokaryote

Examples are Plants, Animals, Fungi and Protists

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Prokaryotes

•First cell type on earth

•Cell type of Bacteria and Archaea

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Eukaryotes

Plant Cell Animal Cell

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Prokaryotes & Eukaryotes

The human eye can see objects larger than about 0.5 mm. Most of what interests cell biologists, however, is much smaller than that. Microscopes make seeing the cellular and subcellular world possible.

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Cell Theory

1. Cells are the basic unit of life.

2. Every organism is made up of cells. (Schwann & Schleiden)

3. Every cell comes from pre-existing cells. (Virchow)

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What do cells do?

Basically,

1. Cells acquire and synthesize energy

2. Cells synthesize proteins

3. A cell makes more copies of itself

ATP

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What are the basic structures of

a Eukaryotic cell?

1. Cell Membrane – controls what gets

in and out of the cell

2. Cytoplasm – where organelles float

& chemical reactions occur

3. Nucleus – control center of the cell

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Cell Parts & Organelles

Organelles are cell parts that have specificfunctions. Organelles do the work of cells.Each structure has a job to do. Organelleskeep the cell alive. Functions are the ff:

1. Organelles that store, clean-up, & support

2. Organelles that build proteins

3. Organelles that capture & release energy

4. Cellular boundaries

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Organelles that store, clean-up, & support

1. Vacuoles – storage tanks

2. Vesicles – smaller than a vacuole,transports substances

3. Lysosomes – suicidal bags/ recyclebins

4. Centrioles – for cell division

5. Cytoskeleton – skeletal system of thecell

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Plant Cells

contractile

vacuole

Animal Cells

central vacuole food vacuole

Protist Cells

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Vacuoles & Vesicles• Function

• moving material around cell

• storage

• Structure

• membrane sacsmall food

particle

vesicl

e

vacuole filled w/

digestive enzymes

vesicle filled w/

digested nutrients

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Lysosomes

small food

particle

vacuole

digesting food

lysosomes

• Function• digest food

• used to make energy

• clean up & recycle• digest broken

organelles

• Structure• membrane sac of

digestive enzymes

digesting brokenorganelles

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A Job for Lysosomes

15 weeks

6 weeks

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Centrioles

•Function• help coordinate cell

division• only in animal cells

•Structure• one pair in each

cell

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Cytoskeleton• Filaments & fibers

• Made of 3 fiber types• Microfilaments

• Microtubules

• Intermediate filaments

• 3 functions:• mechanical support

• anchor organelles

• help move substances

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A = actin, IF = intermediate filament, MT = microtubule

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Cilia & Flagella• Provide motility

• Cilia • Short

• Used to move substances outside human cells

• Flagella• Whip-like extensions

• Found on sperm cells

• Basal bodies like centrioles

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Cilia & Flagella Structure• Bundles of microtubules

• With plasma membrane

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Organelles that build proteins

1. Ribosomes – protein factories

2. Endoplasmic Reticulum – passageway/ roadways

A. Rough ER

B. Smooth ER

3. Golgi bodies – transport/ vehicles

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Ribosomes on ER

Ribosomes & ER

• Function

• protein factories

• read instructions to build proteins from DNA

• Structure

• some free in cytoplasm

• some attached to ER

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• Function• works on proteins

• helps complete the proteins after ribosome builds them

• makes membranes

• Structure• rough ER

• ribosomes attached

• works on proteins

• smooth ER• makes membranes

Endoplasmic Reticulum

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transport vesicles

vesiclescarrying proteins

• Function• finishes, sorts, labels &

ships proteins• Like a logistics service

• shipping & receiving department

• ships proteins in vesicles• “logistics trucks”

• Structure• membrane sacs

Golgi Apparatus

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Organelles that capture & release energy

1. Chloroplasts – convert solar energy into chemical energy; found only in autotrophs; “solar power plant”

2. Mitochondria – powerhouse of the cell; “power plant”

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•Function• make ATP energy

from cellular respiration• sugar + O2 ATP

• fuels the work of life

•Structure• double membrane

Mitochondria

ATP

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Chloroplasts•Derived form photosynthetic bacteria

•Solar energy-capturing organelle

•Structure:•double membrane

•Thylakoid

•Stroma

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Colored organelles (plastids)a) Chromoplast – red

b) Leucoplast – colorless

c) Chloroplast – green

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Cellular boundaries

1. Cell Membrane (Plasma Membrane) –regulates the entrance & exit of substance

2. Cell Wall – shapes, supports, protects

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Plasma Membrane

•Contains cell contents

•Double layer of phospholipids & proteins

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Fluid-Mosaic ModelIt explains the structure of the cell membrane (Singer and Nicholson, 1980s).

Polar heads

love water

& dissolve.

Non-polar

tails hide

from water.Proteins

Carbohydrate

cell markers

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Phospholipids

Nature:

Amphipathic

Structure:• Hydrophilic head

• Hydrophobic tail

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Movement Across the Plasma Membrane

A few molecules move freely:• Water, Carbon dioxide, Ammonia, Oxygen

Carrier proteins transport some molecules• Proteins embedded in lipid bilayer

• Fluid mosaic model – describes fluid nature of alipid bilayer with proteins

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Membrane Proteins

1. Channels or transporters• Move molecules in one direction

2. Receptors • Recognize certain chemicals

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Membrane Proteins

3. Glycoproteins

• Identify cell type

4. Enzymes

• Catalyze production of substances

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Cell Walls

• Found in plants, fungi, & many protists

• Surrounds plasma membrane

• Plants – cellulose

• Fungi – contain chitin

• Bacteria – peptidoglycan

• Protists – cellulose & pectin

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