Transcript Topic 2.3 - biology4friends

IB Biology
2 Cells
2.3 Eukaryotic Cells
All syllabus statements ©IBO 2007
All images CC or public domain or link to original material.
Jason de Nys
http://commons.wikimedia.org/wiki/File:Biological_cell.svg
2.3.1.
Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell
2.3.2 Annotate the diagram from 2.3.1 with the functions of each named structure.
The Nucleus contains
the chromosomes
which comprise most
of the DNA in a cell
- It is the largest
organelle
- It has a double layer
membrane
- mRNA, transcribed
from the DNA in the
nucleus, exits through
pores more in 3.3, 3.4 and 7.1 and 7.2
- Some cells have
multiple nuclei
The bright blue stains are nuclei in HeLa
cells. Read “The Immortal Life of
Henrietta Lacks” for a fascinating story
of the origin of HeLa cells
http://commons.wikimedia.org/wiki/File:HeLa_cells_stained_with_Hoechst_33258.jpg
http://commons.wikimedia.org/wiki/File:Diagram_human_cell_nucleus.svg
The Cell membrane is the boundary of the cell.
• It acts as a “gatekeeper”, preventing the entry or exit of some
molecules and facilitating the movement of others.
• It is a phospholipid bilayer
• It is permeable to oxygen and carbon dioxide
• It is impermeable to water and charged particles, they must
enter through special proteins embedded in the membrane
More in 2.4
http://commons.wikimedia.org/wiki/File:Cell_membrane_detailed_diagram_en.svg
The Mitochondrion (pl. Mitochondria)
• The ‘power house’ of the cell
• Has a smooth outer membrane and
a folded inner membrane
• Where aerobic respiration occurs in
the cell
More in 3.7 and 8.1
Mitochondria in mammalian lung cells
Remember:
Where else do we see loops of DNA?
How does the size of a mitochondrion
compare with an average prokaryote?
The implications of the answers to these
questions are in Option D: Evolution
http://commons.wikimedia.org/wiki/File:Animal_mitochondrion_diagram_en.svg
http://commons.wikimedia.org/wiki/File:Mitochondria,_mammalian_lung_-_TEM.jpg
Rough Endoplasmic Reticulum
Spot the
difference?
Smooth Endoplasmic Reticulum
http://images.wellcome.ac.uk/
The ‘spots’ are the
difference!
The Rough Endoplasmic
Reticulum is peppered with
ribosomes that give it the
rough appearance
It is where protein synthesis
occurs
more in 3.5 and 7.4
The (free) Ribosome, the
molecular machine
responsible for protein
synthesis
much, much more in 3.5 and 7.4
A ribosome on
the sculpture
“Waltz of the
Polypeptides” at Cold Spring Harbor Laboratory
http://www.flickr.com/photos/cryo_mariena/6033827307/sizes/m/in/photostream/
I shall name it………
The internal reticular apparatus!!
Pretty catchy… no?*
Camillo
Golgi
*Everybody thought that was a terrible
name, so they called it the Golgi
apparatus instead
http://commons.wikimedia.org/wiki/File:C_Golgi.jpg
http://commons.wikimedia.org/wiki/File:Golgi_in_the_cytoplasm_of_a_macrophage_in_the_alveolus_(lung)_-_TEM.jpg
The Golgi Apparatus is a flattened
stack of membranes responsible
for the packaging and delivery of
proteins
http://en.wikipedia.org/wiki/File:Nucleus_ER_golgi.svg
Lysosomes are simple, membrane-bound organelles
full of enzymes that digest engulfed bacteria and
viruses and large molecules
for recycling.
http://commons.wikimedia.org/wiki/File:Lysosome.jpg
Image from an amazing site by teacher Andrew Brown
http://www.tokresource.org/tok_classes/biobiobio/biomenu/eukaryotic_cells/index.htm
2.3.3 Identify structures from 2.3.1 in electron micrographs of liver cells.
Rough Endoplasmic Reticulum
Mitochondrion
Smooth Endoplasmic Reticulum
What can you see?
2.3.4 Compare prokaryotic and eukaryotic cells
Compare Give an account of similarities and differences between
two (or more) items, referring to both (all) of them throughout
Prokaryotic
Eukaryotic
Small cells
Relatively larger cells
Always unicellular
Some multicellular, some unicellular
No nucleus: DNA a ‘naked’ loop in the
nucleoid region
DNA in chromosomes in a membranebound nucleus
Ribosomes smaller (70s)
Ribosomes larger (80s)
No mitochondria, respiration in cell
membrane and mesosomes
Mitochondria, where aerobic respiration
occurs
Cell division by binary fission
Cell division by meiosis or Mitosis
Reproduction asexual (some gene
exchange can occur via conjugation)
Reproduction Sexual or asexual
Table modified from Click4Biology
2.3.5 State three differences between plant and animal cells
State: Give a specific name, value or other brief answer without
explanation or calculation.
Animals
Plants
Have a cell wall
Don’t have a cell wall
Have chloroplasts in photosynthetic cells
Don’t have chloroplasts anywhere
Carbohydrate stored as starch and plant
oils
V.
Carbohydrate stored as glycogen and
animal fat
Rigid Shape (due to cell wall)
Flexible shape
Have a large permanent storage vacuole
May have small, temporary vacuoles
http://www.flickr.com/photos/chubbybat/45407031/
http://www.flickr.com/photos/powi/749366522/
2.3.6 Outline two roles of extracellular components
Outline:
Give a brief
account or
summary.
Got a banana?
Bone cells have an
extracellular matrix in
the interstitial spaces
(between the cells)of
collagen and calcium
phosphate; which
together form the hard
bone.
http://www.flickr.com/photos/limonada/14705232/
The other form of
extracellular matrix is the
basement membranes
They exist in many tissue
types as a form of support
e.g. as the lining in blood
vessels
You may already know about the
glomerulus in the kidney. A basement
membrane is integral to ultrafiltration
there.
More in HL 11.3
http://commons.wikimedia.org/wiki/File:Gallbladder_cholesterolosis_low_mag.jpg
As well as extracellular
matrices in animals,
plant have extracellular
components….
Cell Walls
They are made of cellulose and provide
structure, support and protection. They
maintain cell shape and
prevent turgor pressure
from rupturing the cell
http://www.flickr.com/photos/ah_pao/2590017159/
Further information:
Three of the best sites for
IB-specific Biology
information. The top link
takes you to the PPT by
Stephen Taylor