biodasTaMu2 MetIl SFCell 19-22 Sep

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TaMu2:

Metode Ilmiah;

Struktur dan Fungsi Sel

19/22 September 2011

Tahun Ajaran 2011/2012



Scientists use two main forms of inquiry in

their study of nature

• There are two main types of scientific

inquiry

– discovery science

– hypothesis-based science

• Discovery science describes natural

structures and processes

– This approach is based on observation and theanalysis of data

K3: Mahasiswa mampu menerangkan proses metode ilmiah; K4: Mahasiswa

mampu membedakan discovery science dari hypothesis-based science



Types of Data

• Data are recordedobservations or itemsof information

– Qualitative, or

descriptions rather than measurements

– Quantitative, or recordedmeasurements,

which aresometimesorganized into tablesand graphs

K3,K4



Induction in Discovery Science

• Inductive reasoning draws conclusions

through the logical process of induction

• Repeat specific observations can lead to

important generalizations – For example, “All organisms are made of cells”

K3;K4; K5: Mahasiswa mampu membedakan induksi dari deduksi



Hypothesis-Based Science

• Observations can lead us to ask questionsand propose hypothetical explanations

called hypotheses

K3;K4; K5; K6: Mahasiswa mampu merumuskan hipotesis ilmiah

The Role of Hypotheses in Inquiry

• A hypothesis is a tentative answer to a

well-framed question

• A scientific hypothesis leads to predictions

that can be tested by observation or

experimentation



• For example,

– Observation: Your flashlight

doesn’t work

– Question: Why doesn’t your

flashlight work?

– Hypothesis 1: The batteries

are dead

– Hypothesis 2: The bulb is

burnt out• Both these hypotheses are

testable

Observations

Question

Hypothesis #1:

Dead batteries

Hypothesis #2:Burnt-out bulb

Prediction:

Replacing batterieswill fix problem

Prediction:

Replacing bulbwill fix problem

Test prediction Test prediction

Test falsifies hypothesis Test does not falsify hypothesis

K3;K4; K5; K6



Deduction: The “If…Then” Logic of Hypothesis

Based Science

• Deductive reasoning uses general

premises to make specific predictions

• For example, if organisms are made of cells

(premise 1), and humans are organisms

(premise 2), then humans are composed of

cells (deductive prediction)

K3;K4; K5; K6



Theories in Science

• In the context of science, a theory is:

– Broader in scope than a hypothesis

– General, and can lead to new testable

hypotheses – Supported by a large body of evidence in

comparison to a hypothesis



K7: Mahasiswa mampu membedakan sel prokariot dari sel eukariot

1. Eukaryotic cells have internal membranes that

compartmentalize their functions

• The basic structural and functional unit of every organism is one of two types of cells:prokaryotic or eukaryotic

• Basic features of all cells: – Plasma membrane

– Semifluid substance called cytosol

– Chromosomes (carry genes)

– Ribosomes (make proteins)



Fimbriae

Nucleoid

Ribosomes

Plasma membrane

Cell wall

Capsule

Flagella

Bacterialchromosome

(a) A typical rod-shapedbacterium

ENDOPLASMIC RETICULUM(ER)

Smooth ERRough ERFlagellum

Centrosome

CYTOSKELETON:

Microfilaments

Intermediatefilaments

Microtubules

Microvilli

Peroxisome

MitochondrionLysosome

Golgiapparatus

Ribosomes

Plasmamembrane

Nuclear envelope

Nucleolus

Chromatin

NUCLEUS


Comparing Prokaryotic and Eukaryotic Cells




Comparing Prokaryotic and Eukaryotic Cells

• Prokaryotic cells are characterized by having – No nuclear envelope

– DNA in an unbound region called the nucleoid

– No membrane-bound organelles

• Eukaryotic cells are characterized by having

– DNA in a nucleus that is bounded by a

membranous nuclear envelope

– Membrane-bound organelles

• Eukaryotic cells are generally much larger

than prokaryotic cells



Eukaryotic Cells

ENDOPLASMIC RETICULUM (ER)

Smooth ERRough ER

Flagellum

Centrosome

CYTOSKELETON:

Microfilaments


Microtubules

Microvilli

Peroxisome

MitochondrionLysosome

Golgiapparatus

Ribosomes

Plasmamembrane

Nuclear envelope

Nucleolus

Chromatin

NUCLEUS

NUCLEUS

Nuclear envelope

Nucleolus

Chromatin

Rough endoplasmicreticulum

Smoothendoplasmicreticulum

Ribosomes

Central vacuole

Microfilaments


Microtubules

CYTO-SKELETO

Chloroplast

Plasmodesmata

Wall of adjacent cell

Cell wall

Plasmamembrane

Peroxisome

Mitochondrion

Golgi

apparatus




2. The eukaryotic cell’s genetic instructions are housed in

the nucleus and carried out by the ribosomesFig. 6-10

NucleolusNucleus

Rough ER

Nuclear lamina (TEM)

Close-up o f nuclear envelope

1 µm

1 µm

0.25 µm

Ribosome

Porecomplex

Nuclear po re

Outer membraneInner membraneNuclear envelope:

Chromatin

Surface of nuclear envelope

Pore complexes (TEM)K7



Cytosol

Endoplasmic reticulum (ER)

Free ribosomes

Bound ribosomes

Largesubunit

Smallsubunit

Diagram of a ribosomeTEM showing ER and r ibosomes

0.5 µm

K7;K8: Mahasiswa mampu membedakan ribosom bebas dari ribosom terikat

Function?



3. The endomembrane system regulates protein traffic and

performs metabolic functions in the cell

• Components of the endomembrane

system:

– Nuclear envelope, Endoplasmicreticulum, Golgi apparatus, Lysosomes,

Vacuoles, Plasma membrane

• These components are either

continuous or connected via transfer by vesicles

K9; K11-12: Mahasiswa mampu mendeskrip struktur dan fungsi sistem endom.



Fig. 6-16-1

Smooth ER

Nucleus

Rough ER

Plasmamembrane



Fig. 6-16-2

Smooth ER

Nucleus

Rough ER

Plasmamembrane

cis Golgi

trans Golgi





K11-12; K9: Mahasiswa mampu membedakan ER halus dari ER kasar

The Endoplasmic

Reticulum: Biosynthetic

Factory

Smooth ER

Rough ER Nuclear envelope

Transitional ER

Rough ERSmooth ER

Transport vesicleRibosomes

Cisternae

ER lumen

200 nm

• The ER membrane is

continuous with the

nuclear envelope

• There are two distinctregions of ER:

Smooth ER, which

lacks ribosomes

Rough ER, with

ribosomes studding

its surface



• Functions of Smooth ER

– Synthesizes lipids

– Metabolizes carbohydrates

– Detoxifies poison

– Stores calcium

• Functions of Rough ER

– Has bound ribosomes, which secrete

glycoproteins (proteins covalently bonded to

carbohydrates)

– Distributes transport vesicles (proteinssurrounded by membranes)

– Is a membrane factory for the cell

K9: Mahasiswa mampu membedakan ER halus dari ER kasar



The Golgi Apparatus: Shipping and

Receiving Center

K11; K12

cis face(“ receiving” side of

Golgi apparatus)Cisternae

trans face

(“ shipping” side of

Golgi apparatus)TEM of Golgi apparatus

0.1 µm



K11; K12

• The Golgi apparatus consists of flattened

membranous sacs called cisternae

• Functions of the Golgi apparatus: – Modifies products of the ER

– Manufactures certain macromolecules

– Sorts and packages materials into transport

vesicles



K11; K12

Lysosomes: Digestive Compartments

Nucleus1 µm

Lysosome

Digestive

enzymesLysosome

Plasma

membrane

Food vacuole

(a) Phagocytosis

Digestion

(b) Autophagy

Peroxisome

Vesicle

Lysosome

Mitochondrion

Peroxisome

fragment

Mitochondrion

fragment

Vesicle containingtwo damaged organelles

1 µm

Digestion



K11; K12

• A lysosome is a membranous sac of

hydrolytic enzymes that can digestmacromolecules

– Lysosomal enzymes can hydrolyze proteins,fats, polysaccharides, and nucleic acids

• A lysosome fuses with the food vacuoleand digests the molecules

• Lysosomes also use enzymes to recyclethe cell’s own organelles andmacromolecules, a process calledautophagy



Vacuoles: Diverse Maintenance Compartments

K11; K12

Central vacuole

Cytosol

Centralvacuole

Nucleus

Cell wall

Chloroplast

5 µm



K11; K12

• A plant cell or fungal cell may have one or several vacuoles

– Food vacuoles are formed by phagocytosis

– Contractile vacuoles, found in many

freshwater protists, pump excess water out of cells

– Central vacuoles, found in many mature

plant cells, hold organic compounds and

water



•Mitochondria and chloroplasts – Are not part of the endomembrane

system

– Have a double membrane – Have proteins made by free ribosomes

– Contain their own DNA

4. Mitochondria and chloroplasts change energy

from one form to another

K10: Mahasiswa mampu menerangkan peran mitokondria, kloroplas





K10: Mahasiswa mampu menerangkan peran mitokondria, kloroplas

Chloroplasts: Capture of Light Energy

• Chloroplast structure includes: – Thylakoids, membranous sacs, stacked to

form a granum – Stroma, the internal fluid

Ribosomes

Thylakoid

Stroma

Granum

Inner and outer membranes

1 µm



5. Extracellular components and connections

between cells help coordinate cellular activities

• Most cells synthesize and secrete

materials that are external to the plasma

membrane

• These extracellular structures include:

– Cell walls of plants

– The extracellular matrix (ECM) of animal cells

– Intercellular junctions

K11: Mahasiswa mampu mendeskripsikan empat macam hubungan antar sel



Cell Walls of Plants

Secondary

cell wall

Primary

cell wall

Middle

lamella

Central vacuoleCytosol

Plasma membrane

Plant cell walls

Plasmodesmata

1 µm

K13

• Plant cell walls

are made of

cellulose fibers

embedded in

other polysaccharides

and protein





Intercellular Junctions

• Neighboring cells in tissues, organs, or organ systems often adhere, interact, and

communicate through direct physical

contact

• Intercellular junctions facilitate this contact

– Plasmodesmata

– Tight junctions

– Desmosomes – Gap junctions

K13



Plasmodesmata in Plant Cells

• Plasmodesmata are channels that perforate

plant cell walls

• Through plasmodesmata, water and small

solutes (and sometimes proteins and RNA) can

pass from cell to cell

K13

Interior of cell

Interior of cell

0.5 µm Plasmodesmata Plasma membranes

Cell walls



Tight Junctions,

Desmosomes, and

Gap Junctions in Animal Cells

K13

Tight junction

0.5 µm

1 µmDesmosome

Gap junction

Extracellular matrix

0.1 µm

Plasma membranesof adjacent cells

Spacebetweencells

Gap junctions

Desmosome


Tight junction

Tight junctions preventfluid from moving

across a layer of cells



• At tight junctions,

membranes of neighboringcells are pressed together,preventing leakage of extracellular fluid

• Desmosomes (anchoring junctions) fasten cells together into strong sheets

• Gap junctions(communicating junctions)provide cytoplasmic channelsbetween adjacent cells

K13

Extracellular matrix

Plasma membranesof adjacent cells

Spacebetweencells

Gap junctions

Desmosome

Intermediate

filaments

Tight junction

Tight junctions preventfluid from movingacross a layer of cells



Summary

1. Eukaryotic cells have internal membranes thatcompartmentalize their function

2. The eukaryotic cell’s generic instructions arehoused in the nucleus and carried out by theribosomes

3. The endomembrane system regulate proteintraffic and performs metabolic functions in thecell

4. Mitochondria and chloroplasts change energy

from one form to another 5. Extracellular components and connections

between cells help coordinate cellular activities



Next Week

Sel II:

Struktur dan Fungsi Membran Sel;

Metabolisme

biodasTaMu2 MetIl SFCell 19-22 Sep

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