SBI3U7 Cell Structure & Organelleslorenowicz.weebly.com/uploads/4/6/1/6/4616010/sbi3u7...Organelles The Structure and Function of the following organelles will be discussed: – Cell

SBI3U7Cell Structure & Organelles

2.2 Prokaryotic Cells 2.3 Eukaryotic Cells

Wednesday, February 6, 2013

2

Prokaryotic Cells Eukaryotic CellsNo nucleus Has a nucleusNo membrane bound organelles Membrane bound organelles

Unicellular Unicellular or multicellularNaked circular DNA, no chromosomes DNA associated with proteins,

wound into chromosomesNo mitochondria Mitochondria for respiration

70s ribosomes 80s ribosomes

ie Bacteria like E. coli

ie cells found in animal, plant and fungi


Prokaryotic Cell


Cilia and Flagella

Both are made of fine protein fibres

Both can be used for locomotion

Cilia: short, may be numerous on cell surface

Flagella: long, usually few in number on cell surface

Pili: used for attachment to other bacteria (used in sexual reproduction)


Prokaryotic Cells divide by binary fission


Structure and Function of Organelles

The Structure and Function of the following organelles will be discussed:

– Cell Membrane– Nucleus– Cell Wall– Cytoplasm– Cytoskeleton– Ribosomes– Endoplasmic Reticulum– Golgi Apparatus

– Mitochondria– Lysosomes– Cilia and Flagella– Centrioles– Vacuoles– Plastids


Plant Cell

Electron micrograph of a typical plant cell

Note: mitochondria in red, nucleus in green, plastids in yellow


Animal Cell

Electron micrograph of a typical animal cell

Note: mitochondria in red, nucleus in peach, endoplasmic reticulum in blue


Animal vs. Plant Cell

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Nucleus Directs all

activities of the cell

Electron micrograph of a nucleus

Note: nucleolus in center of nucleus, endoplasmic reticulum and ribosomes just outside of nucleus


Components of the Nucleus

Chromatin: stringy material made of proteins and DNA that takes up the majority of the nucleus

Nuclear Envelope: double-layered membrane surrounding the nucleus. Contains nuclear pores to allow material to pass in and out.

Chromosomes: condensed chromatin; just before the cell begins to divide the chromatin condenses into chromosomes

Nucleolus: a dense area within the nucleus; the location for production of ribosomes


Endoplasmic Reticulum The ER is a twisting

network of canals and sacs extending through the cytoplasm and connecting the cell membrane to the nuclear membrane

The ER may have ribosomes attached to it (rough ER)

The ER serves to transport products (e.g. proteins) within the cell


Rough vs. Smooth ER

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rER sER

Contain many ribosomes Contains many enzymes

Protein synthesis Multiple functions (in liver cells, breaks down toxins) Also produces phospholipids (used in construction of membranes)


Golgi Apparatus

The Golgi apparatus are sacs of membranous plate-like bags which produce vesicles (sacs)

They function to produce and store cellular secretions

Many proteins and lipids undergo final processing in the Golgi apparatus


Mitochondria Mitochondria are the site of

aerobic cellular respiration Cellular respiration is the

process that converts sugar energy into adenosine triphosphate (ATP) for storage (overall reaction: sugar + O2 CO2 + H2O + ATP energy)

ATP is used by other organelles & cell processes for energy

Cells that respire rapidly (like muscle cells) have numerous mitochondria


Mitochondrial structures Cristae: site of

chemical reactions using embedded proteins (greatly increase the surface area)

Matrix: mitochondrion cytosol

Mitochondrial DNA: self replicating organelle, produces its own unique proteins


Lysosomes

Membrane bound sacs that are used for digestion of various structures within the cell

An acidic environment along with hydrolytic enzymes within lysosomes help to digest particles

Usually not in plant cells


(a) Identify the structures labelled I and II. (2)

(b) State one function of the structure labelled II. (1)

(c) Deduce, with a reason, whether this cell is eukaryotic or prokaryotic. (1)

(Total 4 marks)

Exam Question


Mitochondrion

Eukaryotic: internal membranes / membrane bound organelles / presence of mitochondria / double nuclear membrane;

I: membrane / (nuclear) envelopeII: mitochondrion / mitochondria

Function of mitochondrion (II):aerobic respiration;correct specific reaction / pathway occurring in mitochondria / ATP production; Do not accept “energy production” alone.

Exam Question Example #7Markscheme


Ribosomes Ribosomes are

microscopic spheres attached to the ER or free-floating in the cytoplasm

Ribosomes are protein factories

Ribosomes are made of several components:

Two protein subunits & rRNA Small subunit

Larger subunit


Ribosomes Bound ribosomes: attached to

the ER generally proteins

synthesized by bound ribosomes are secreted by the cell

Free ribosomes: suspended in cytosol generally proteins

synthesized by free ribosomes remain in the cell


Cell Membrane

Functions of cell membrane: protects cell from outside environment; keeps cell contents together; and selectively allows materials to cross into & out of cell.


Cell Membrane


Cell Membrane

Phospholipid: composed of a phosphate “head” and fatty acid “tails.” Hydrophilic Head is “water loving” or soluble in water. Hydrophobic Tails are “water hating” or insoluble in water.

Proteins: “float” around within the membrane or on its surface; functions include: structural support, surface binding sites for molecules like hormones, recognition sites for cell to cell communication & interaction, transport molecules across the membrane, transport electrons & protons within the membrane

Glycocalyx: carbohydrate chains attached to proteins (glycoproteins), involved in recognition & communication proteins, points for cell to cell attachment

Cholesterol: keeps the phospholipids stable and helps retain the membrane‘s shape


Chloroplasts

Chloroplasts are found only in green plants

They convert sunlight to chemical energy via photosynthesis: sunlight + CO2 + H2O -> sugar + O2)


Chloroplast structures

Stroma: chloroplast cytosol Lamella: membrane that attaches inner

chloroplast structures Thylakoid disk: have a specialized membrane

for photosynthesis Grana: stack of thylakoid discs Chloroplast DNA: self-replicating organelle


Vacuoles

Vacuoles contain water and salts

It exerts pressure from within, making the cell turgid and firm

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Extracellular Components Outside of the

cell is called Extracellular Matrix (ECM)

Animal cells secrete glycoproteins to form the ECM

Helps in support, adhesion and movement 28


Identify the following parts Identify part I & II What type of cell

is shown? How do you know?

I is Chloroplast II is nucleus Plant cell since

they contain chloroplasts

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I

IIWednesday, February 6, 2013

Identify part I, II & III

Is this cell eukaryotic or prokaryotic?

I is Golgi apparatus

II is Nuclear pore III is Nucleolus Eukaryotic

30

I

II

III

Identify the following parts


Identify I & II What is the function

of II?

I is Rough ER II is Ribosomes Protein synthesis

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Identify the following partsI II


Documents

SBI3U7 Cell Structure & Organelleslorenowicz.weebly.com/uploads/4/6/1/6/4616010/sbi3u7...Organelles The Structure and Function of the following organelles will be discussed: – Cell