1.2.U3Electron microscopes have a much higher … … · Web viewA smooth outer membrane (2) and a folded inner membrane (1). The folds are referred to as cristae (3). The space in

1. Cell Biology (Core) – 1.2 Ultrastructure of cells

Name:

Topic 1.2 – Ultrastructure of CellsEssential idea: Eukaryotes have a much more complex cell structure than prokaryotes.

Understandings, Applications and Skills (This is what you maybe assessed on)

Statement Guidance1.2.U1 Prokaryotes have a simple cell structure without

compartmentalization.

1.2.U2 Eukaryotes have a compartmentalized cell structure.

1.2.U3 Electron microscopes have a much higher resolution than light microscopes.

1.2.A1 Structure and function of organelles within exocrine gland cells of the pancreas and within palisade mesophyll cells of the leaf.

Textbook Page 24

1.2.A2 Prokaryotes divide by binary fission.

1.2.S1 Drawing of the ultrastructure of prokaryotic cells based on electron micrographs.

Drawings of prokaryotic cells should show the cell wall, pili and flagella, and plasma membrane enclosing cytoplasm that contains 70S ribosomes and a nucleoid with naked DNA.

1.2.S2 Drawing of the ultrastructure of eukaryotic cells based on electron micrographs.

Drawings of eukaryotic cells should show a plasma membrane enclosing cytoplasm that contains 80S ribosomes and a nucleus, mitochondria and other membrane-bound organelles are present in the cytoplasm. Some eukaryotic cells have a cell wall.

1.2.S3 Interpretation of electron micrographs to identify organelles and deduce the function of specialized cells.

1.2.U3Electron microscopes have a much higher resolution than light microscopes. AND Nature of Science: Developments in scientific research follow improvements in apparatus—the invention of electron microscopes led to greater understanding of cell structure. (1.8)

Electron microscopes use ___________________________ focused by _______________ to magnify and resolve microscopic specimens

• Transmission electron microscopes (TEM) generate high resolution cross-sections of objects• Scanning electron microscopes (SEM) display enhanced depth to map the surface of objects in 3D

Electron microscopes have two key advantages when compared to light microscopes:• They have a much ___________________________________ (can detect smaller structures)• They have a much ___________________________________ (can provide clearer and more

detailed images)

Some disadvantage of electron microscopes are that they cannot display living specimens in ____________

1.2.U1Prokaryotes have a simple cell structure without compartmentalization. 1.2.S1 Drawing of the ultrastructure of prokaryotic cells based on electron micrographs.

http://www.bioknowledgy.info/ (Chris Paine)

Prokaryotes are organisms whose cells _______________________________ ('pro' = before ; 'karyon' = nucleus)

They belong to the kingdom __________________ and have been further classified into two distinct domains:

• ___________________________ – found in extreme environments like high temperatures, salt concentrations or pH (i.e. extremophiles)

• ___________________________ – traditional bacteria including most known pathogenic forms (e.g. E. coli, S. aureus, etc.)

Prokaryotic FeaturesProkaryotic cells will typically contain the following cellular components:cytoplasm

region of the cytoplasm where the DNA is located (DNA strand is circular and called a genophore)

Nuceloid

complexes of RNA and protein that are responsible for polypeptide synthesis (prokaryote ribosome = 70S)

Ribosome

Semi-permeable and selective barrier surrounding the cellCell Wall

a thick polysaccharide layer used for protection against dessication (drying out) and phagocytosis

Flagella

Hair-like extensions that enable adherence to surfaces (attachment pili) or mediate bacterial conjugation (sex pili)


Prokaryotes reproduce _________________ using the process of binary fission• The DNA is replicated __________________________ [2.7.U1]• The two ______________ attach to the membrane• The membrane elongates and pinches off (_________________) forming two separate cells• The two daughter cells are ____________________________________ (clones)• Binary fission is also used by some organelles in eukaryotes [links to 1.5.U3]


1.2.S1 Drawing of the ultrastructure of prokaryotic cells based on electron micrographs.

Key Features:Pili – shown as single lines

Flagella – shown as thicker and significantly longer lines than the pili

Ribosomes – labelled as 70S

Cell wall – labelled as being composed of peptidoglycan; thicker than cell membrane

Shape – appropriate for bacteria chosen (e.g. E. coli is a rod-shaped bacillus)

Size – appropriate dimensions (e.g. length of cell twice the width)

1.2.U2Eukaryotes have a compartmentalized cell structure.There are several advantages in being compartmentalized:

• ____________________________ - enzymes and substrates can localized and much more concentrated

• ____________________________ - pH and other such factors can be kept at optimal levels. The optimal pH level for one process in one part of the cell

• ____________________________________ e.g. digestive enzymes (that could digest the cell itself) are stored in lysosomes

• __________________________________________ dependent on the cell’s requirements.

Eukaryotes are organisms whose cells ____________________________________________ (‘eu’ = good / true ; ‘karyon’ = nucleus)

• They have a _____________________ structure and are believed to have evolved from _________________ cells (via endosymbiosis)

• Eukaryotic cells are compartmentalized by ______________________ structures (organelles) that perform specific roles

Eukaryotes can be divided into four distinct kingdoms:• ____________ – unicellular organisms; or multicellular organisms without specialized tissue• Fungi – have a cell wall made of ____________ and obtain nutrition via

__________________________ (decomposers)• Plantae – have a cell wall made of ______________ and obtain nutrition _______________ (via

photosynthesis)• Animalia – _______________ and obtain nutrition via heterotrophic ingestion


1.2.A1 Structure and function of organelles within exocrine gland cells of the pancreas and within palisade mesophyll cells of the leaf.Organelle Function Diagram (labelled) How to identify it

Nucleus

Mitochondrion Site of ATP production by aerobic respiration (if fat is used as a source of energy it is digested here)

Has a double membrane. A smooth outer membrane (2) and a folded inner membrane (1). The folds are referred to as cristae (3). The space in the middle is called the matrix (4). The shape varies.

Freeribosomes(80S)

Rough Endoplasmic Reticulum(rER)

Golgi Apparatus

Vesicles

Lysosomes

Vacuoles


Organelle Function Diagram (labelled where necessary)

How to identify it on an electron micrograph

Flagellum

Cilia

Microtubules andcentrioles

Chloroplast


Key Features:Nucleus – shown as double membrane structure with poresMitochondria – double membrane with inner one folded into cristae ; no larger than half the nucleus in sizeGolgi apparatus – shown as a series of enclosed sacs (cisternae) with vesicles leading to and fromEndoplasmic reticulum – interconnected membranes shown as bare (smooth ER) and studded (rough ER)Ribosomes – labelled as 80S

Cytosol – internal fluid labelled as cytosol (‘cytoplasm' is all internal contents minus the nucleus)


Key Features:Vacuole – large and occupying majority of central space (surrounded by tonoplast)Chloroplasts – double membrane with internal stacks of membrane discs (only present in photosynthetic tissue)Cell wall – labelled as being composed of cellulose ; thicker than cell membraneShape – brick-like shape with rounded corners


Attempts can be made to deduce cell function based on the relative abundance of organelles:Mitochondria – Cells with many mitochondria typically undertake ______________________________________

(e.g. neurons, muscle cells)

ER – Cells with extensive ER networks undertake _________________________________________________________ (e.g. plasma cells, exocrine gland cells)

Lysosomes – Cells rich in lysosomes tend to undertake ______________________________________ (e.g. phagocytes)

Chloroplasts – Cells with chloroplasts undergo ______________________________ (e.g. plant leaf tissue but not root tissue)

Your Turn to Practice1.2.U3Electron microscopes have a much higher resolution than light microscopes. AND Nature of Science: Developments in scientific research follow improvements in apparatus—the invention of electron microscopes led to greater understanding of cell structure. (1.8)

1. State the definition of resolution:

2. Complete the table below comparing the resolution of the eye with light and electron microscopes:

resolution

Millimetres(mm)

Micrometres(μm)

Nanometres(nm)

Human eye 100,000

Light microscopes 0.0002

Electron microscopes

0.001 1


3. Explain why electron microscopes have a better resolution that light microscopes.

4. State what is meant by the term Ultrastructure.

5. The invention of electron microscopes improved the understanding of cell structure. State one thing that electron microscopes can see, but light microscopes cannot.

1.2.U1Prokaryotes have a simple cell structure without compartmentalization. 1.2.S1 Drawing of the ultrastructure of prokaryotic cells based on electron micrographs.6. Prokaryotes have a simple cell structure.

a. Define the term prokaryote.

b. Draw and label the ultrastructure of a generalized prokaryote. Include cell wall, plasma membrane, pili, flagella, nucleoid (naked DNA), ribosomes and a scale bar.

c. Annotate the diagram with the function of each of the labeled parts.

7. This image is a transmission electron micrograph of a bacterium. Identify the labelled structures:

I

II


III

IV


8. Is the process of binary fission asexual or sexual? Compare the genetic content of the two daughter cells with the parent cell.

9. Outline the process of binary fission

1.2.U2Eukaryotes have a compartmentalized cell structure.

10. Plant and animal cells are eukaryotic.a. Define the term eukaryote.

b. Outline the benefits compartmentalisation provides to eukaryote cells compared when with prokaryotes.

c. Draw a 6 Kingdom Diagram with labels and annotations


1.2.A1 Structure and function of organelles within exocrine gland cells of the pancreas and within palisade mesophyll cells of the leaf.

11. Complete the table to summary the organelles commonly found in eukaryotes.


12. Cell walls are not true organelles.a. What is the function of the cell wall and where can it be found?

b. Explain why the cell wall is not considered an organelle.


c. In plant cells what is the cell wall mainly composed of?


13. The ultrastructure of plant and animal cells is very different.a. Distinguish between the structure of plant and animal cells

b. Draw and label the ultrastructure of a generalized eukaryote animal cell. Include all the relevant organelles from the two questions above.

c. Draw and label the ultrastructure of a generalized eukaryote Plant cell. Include all the relevant organelles from the two questions above.

14. The image below shows a TEM micrograph of a liver cell.a. Identify the labeled structures.


b. Calculate the magnification of the image.

c. Calculate the maximum diameter of the nucleus.


15. Deduce the function of each of the following images. For each deduction refer to the identified organelles and argue the evidence.


Citations:

Allott, Andrew. Biology: Course Companion. S.l.: Oxford UP, 2014. Print.Taylor, Stephen. "Essential Biology 02.2 & 02.3 Prokaryotes and Eukaryotes.docx." Web. 19 Aug. 2014. BioNinja - http://ib.bioninja.com.au/welcome-to-the-bioninja/


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1.2.U3Electron microscopes have a much higher … … · Web viewA smooth outer membrane (2) and a folded inner membrane (1). The folds are referred to as cristae (3). The space in