Transcript Structure, function and growth of prokaryote and eukaryote cells

Structure, function and growth of prokaryote
and eukaryote cells
(a) Comparison of features and ultrastructure of
prokaryotic and eukaryotic cells.
True nucleus
‘Before the true nucleus’
•Comparison of DNA, presence or absence of nucleus and
functions of organelles present, membranes and cytosol
organisation
Semi-fluid part of the cytoplasm that
contains structures to support the cells
organelles
Discussion Questions
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What cells are prokaryote / eukaryote?
What structures do all cells have in
common?
What cell structures do you already know?
Eukaryote Cell - plant
Eukaryote Cell - animal
Features of an eukaryote cell…..
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Cell Wall (plants only)
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Plasmodesmata
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Made of Cellulose
Connecting structures between cells that allow a
continuous cytoplasmic link.
Middle Lamella
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Thin layer of material that binds the cell walls of
two adjacent cells together
…features of an eukaryote cell…
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Vacuole (plants = large; animals = small
or absent)
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Membrane around the vacuole controls the
movement of substances into and out of the
vacuole.
Storage reservoir for nutrients, waste
products, enzymes and other metabolites.
Maintains cell turgor
…features of an eukaryote cell…
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Cytosol – fluid part of the cytoplasm which contains components of
the cytoskeleton and in which the cells organelles are suspended.
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Cytoskeleton
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Framework of protein fibres that
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Nucleus
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Nucleosomes
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provides support for the cell membrane
Supports the organelles
Helps the cell move
Provides a surface for chemical reactions
Structures made up of histone proteins, that DNA coils around allowing it to
become tightly packed
Nuclear Membrane
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Double membrane structure with pores
Membrane connects to the endoplasmic reticulum
…features of an eukaryote cell…
…features of an eukaryote cell…
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Endoplasmic reticulum
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Smooth ER
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Rough ER
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Site of biochemical reactions,
in particular phospholipid and
fatty acid synthesis
Has ribosomes attached
Site of protein synthesis
Golgi Apparatus (a.k.a. dictyosome in plants)
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Modifies and packages materials such as proteins and
polysaccharides.
Stores and transports secretory products such as enzymes
and hormones.
…features of an eukaryote cell
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Mitochondria
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Has a double membrane..
Contains its own DNA and ribosomes.
Matrix is the site of the Krebs Cycle.
Cristae (infolded inner membrane) is the site of the
cytochrome system.
Chloroplasts (plants only)
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Grana
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Site of the light stage of photosynthesis
Stroma
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Site of the Calvin cycle (carbon fixation)
…features of an eukaryote cell
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Microvilli (animal only)
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Finger-like projections covered by the cell
membrane.
Increase the absorptive or secretory surface area
of the cell.
Centrioles (animal only)
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Assist in the organisation of the spindle fibres
during cell division
…features of an eukaryote cell…
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Lysosomes
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Membrane bound sac containing enzymes that
digest foreign invaders and unwanted organelles
Microbodies (aka peroxisomes)
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Membrane bound vesicle containing enzymes that
need to be kept separate from the rest of the
cytosol
…features of an eukaryote cell
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Endomembrane
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All the internal membranes of the cell
Ensures the cytosol is organised so that the cell
function can be controlled and regulated
Prokaryote Cell
Features of a prokaryote cell…
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Cell Wall
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Made of peptidoglycan (combination of
polysaccharide and peptide chains)
A staining procedure called a gram stain can be
carried out. Gram positive bacteria have a thicker
cell wall that takes up the stain. Gram negative
bacteria don’t take up the stain
Gram negative bacteria
• Thin layer of peptidoglycan
• Outer membrane
Gram positive bacteria
• Thick layer of peptidoglycan
… features of a prokaryote cell…
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Flagella (singular = Flagellum)
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Pili (a.k.a fimbriae)
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Used for movement
Shorter, straighter and thinner than flagella
Used for attachment
Glycocalyx (Capsule or Slime layer)
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Mucus like layer made of polysaccharide and/or polypeptide
Protects bacteria from enzymes, antibodies and phagocytes
…features of a prokaryote cell…
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Cytosol
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NO NUCLEAR MEMBRANE
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Does have a nuclear region where the DNA tends
to congregate
DNA
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Single circular molecule
DNA highly condensed by coiling and folding to
produce a structure known as a nucleoid.
…features of a prokaryote cell
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Plasmid
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Small circular rings of ‘accessory’ DNA
Replicate independently of the main chromosome
Transferred from cell to cell
Ribosomes
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Site of protein transcription
Learning Activities
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Draw diagrams of prokaryote and
eukaryote cells, with functions of
organelles written in
Create a table that highlights differences
and similarities between prokaryotes and
eukaryotes
Add information to the organelles and cell
structures sheet to include prokaryote
structures
Learning Activities
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Complete the following worksheets
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Bacteria Cells
Identifying TEM Photographs
Identifying Cell Structures
Read DART material (pg 1-8) and take
further notes
Learning Activities
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Look at the following websites (access
from biozone links (cell biology)
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www.cellsalive.com/cells/cell_model.htm
www.wisconline.com/objects/index_tj.asp?objid=AP116
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Try the multichoice questions from past
AH papers