the cell is the lowest level of structure that is capable of performing all the activities of life....
TRANSCRIPT
• The cell is the lowest level of structure that is capable of performing all the activities of life.
• The first cells- cork, Robert ___________ in 1665.
• Anton van ________________ - first saw single-celled organisms in pond water and observed cells in blood and sperm.• In 1839, Matthais Schleiden and Theodor
Schwann – The ________________- all living things
consist of cells.• A cell theory extension - all ______ come from other
_____.
Cell Structure and FunctionChapter 4
Early Discoveries
• Smallest unit of ____
• Can survive _____________ or has
potential to do so
• Is highly organized for __________
• Senses and responds to ____________
• Has potential to ________________
Cell
• Prokaryotic vs eukaryotic cells
•Similarities-
•A ___________________.
•A ______ (semifluid substance) within the cell
•_______________
•__________- organelles that make proteins
•Differences
•Euks have chromosomes in a ____________(compared to a nucleosome in proks.)
•Euks have many _______ __________________
•Eukaryotic cells are __________times larger
• Larger organisms do not generally have _______cells than smaller organisms - simply _______cells.
Structure of Cells
• Main component of cell ____________
• Gives the membrane its _____ properties
• Two layers of ______________
Lipid Bilayer
Fluid Mosaic Model• Membrane is a mosaic of
– _______________– ______________– Sterols– _______________
Membrane Proteins• __________proteins
• _________ proteins
• Recognition proteins
• ___________ proteins
Why Are Cells So Small?• Surface-to-volume ratio
• A bigger cell = less _________________ per unit volume
• Above a certain size, material cannot be moved in or out of cell _____________
0.5 1.0 1.5
0.79
0.06
3.14 7.07
0.52 1.77
Diameter (cm):
Surface area (cm2):
Volume (cm3):
Surface- to-volume ratio: 13.17:1 6.04:1 3.99:1
Fig. 4.5, p. 54
• ___________ microscope -minimum resolution is - _ _______ ( the size of a small bacterium)
For higher resolution--__________ microscope-Transmission Electron Microscope-Scanning Electron Microscope
Microscopy
Fig. 7.7
Animal cell
Animal cells lack:•_____________•_____________•______________•______________
Fig. 7.8
Plant cell
Plant cells lack:•__________•___________•__________
Most other components are __________by plant and animal cells
• contains most of the _____ in a eukaryotic cell.
– Some genes are in ___________ and _____________
• separated from the cytoplasm by a ____________ membrane.
• Protein pores allow large macromolecules and particles to pass through.
• ______________ (located internal to the membrane)- maintains nuclear __________
1. The nucleus
• ___________ (DNA and associated proteins) – Each eukaryotic species has a
characteristic number of _________________.
– A typical human cell has 46 chromosomes, but sex cells (eggs and sperm) have only 23 chromosomes.
• ___________- densely stained fibers and granules adjoining chromatin
•Factory for ribosomal RNA (rRNA)
•rRNA is a component of ______________
_____________-
• contain _______ (from nucleolus) and __________.
• composed of two subunits
• carry out __________ synthesis.
2. Ribosomes build a cell’s proteins
Fig. 7.10
• Found in _______locations-– 1. “_____” ribosomes -suspended in the
cytosol – Function: synthesize ______________ proteins
– 2.”_____” ribosomes- attached to the outside of the __________________________• Function: synthesize __________ proteins
and ____________ proteins– Note: Ribosomes can shift locations.
Ribosomes- (cont.)
• The _____________________- includes
• the nuclear envelope
• endoplasmic reticulum
• Golgi apparatus
• lysosomes
• vacuoles
• plasma membrane.
• Where are the membranes produced?? The _____
• Two regions of ER that differ in structure and function.
– _______ ER
• ribosomes attached to the outside
• Packages proteins into ____________________
– __________ ER
• lacks _____________• Function: synthesize lipids,
including oils, phospholipids, and steroids– Also _________________
drugs and poisonsFig. 7.11
3.The endoplasmic reticulum
• Function: _________, ____, and ______ cell products
• Many transport vesicles from the ER travel to the ________ __________________ for modification of their contents.
4. The Golgi apparatus
Cis face“receiving”
Trans face“shipping”
____ face _______ vesicles from ER; ______ face ships vesicles out
• a membrane-bounded sac of ________ enzymes
• functions -digest ________________ (proteins, fats, polysaccharides, and nucleic acids).
• Low pH (5.0)
5. Lysosomes
Fig. 7.13a
•massive leakage from lysosomes can destroy an cell by __________
Nucleus
Lysosome
• The lysosomal enzymes and membrane are synthesized by ________ and then transferred to the ___________.
• At least some lysosomes bud from the trans face of the ______.
Fig. 7.14
5. Lysosomes (Cont.)
Inherited diseases affect _______________ metabolism:– These individuals lack a functioning version of
a normal hydrolytic enzyme.– Result- Lysosomes are engorged with
______________ substrates.• ____________ disease in the liver • Tay-Sachs disease in the brain.
• Lysosomes can fuse with __________________ or another organelle
5. Lysosomes (Cont.)
• Vesicles and vacuoles (larger versions) are membrane-bound_____ with varied functions.– ___ vacuoles, from
phagocytosis, fuse with lysosomes.
– _________vacuoles, found in freshwater protists, pump excess water out of the cell.
– __________ vacuoles are found in many mature ______cells.• Functions - stockpiling
proteins or inorganic ions….,
6. Vacuoles
• Convert energy to forms that cells can use for work.
• __________ -site of _______ _____________, generating ATP from the catabolism of sugars, fats, and other fuels in the presence of oxygen.
• ___________, found in plants and eukaryotic algae, are the site of ________________.– They convert solar energy
to chemical energy and synthesize new organic compounds from CO2 and H2O.
7. Mitochondria and chloroplasts
Chloroplast
Mitochondria
• Mitochondria and chloroplasts-– Are _____ part of the endomembrane system.
• Proteins from ____ ribosomes in the cytosol (and a few from their own ribosomes).
– Contain DNA– Grow and reproduce as ______________
organelles.
• Almost all ____________ cells have mitochondria.
• Cells may contain one to __________________.
• The number of mitochondria is correlated with aerobic metabolic activity.
• Endoplasmic reticulum
• Ribosomes
• Nucleus
Review
• Nucleolus
DNAProduce mRNA
Produce rRNA (for ribosomes)
Protein synthesis
Produce membranes
FUNCTION
Golgi
Function
Finishes, sorts, and ships _____________
LysosomeNucleus
digest -__________
Vacuole•Food vacuole•Central vacuole (plants)
•Transport food to lysosome•Give plants rigidity
Chloroplast
Mitochondria •Produce ATP for energy
•Capture light for energy (only chloroplasts)
• generate and degrade -_______________ (H2O2) in performing various metabolic functions – H2O2 is _______, but the peroxisome has
another enzyme that converts H2O2 to water.
8. -_______________
•Functions:
• break ___________ down for fuel.
•__________ alcohol (and other harmful compounds).
•Convert the fatty acids in seeds to sugars
•Not part of __________- system
• The ____________ is a network of _______ extending throughout the cytoplasm.
• ________: – Organizes the
structures and activities of the cell.
– provides __________ support and maintains shape of the cell.
– provides ____________ for many organelles and cytosolic enzymes
– dynamic
9. Cytoskeleton
Fig. 7.20
• There are three main types of fibers in the cytoskeleton:
• ______________
• ________________
• __________________.
9. Cytoskeleton (Cont.)
Fig. 7.21b
microfilaments
Intermediate filaments
(Keratin)
(Actin)
Function in plants: _____________, maintains its shape, and prevents excessive uptake of water.– It also supports the plant against the force of
____________.
10. Cell wall – Plant and proks, but not animal cells
• Composed of microfibrils of _______ embedded in a matrix of proteins and other polysaccharides.
•steel-reinforced concrete analogy
Plasma membrane
• Can influence the activity of genes in the nucleus via a combination of chemical and mechanical signaling pathways.
• This may coordinate all the cells within a tissue.
• Function- support, adhesion, movement, and regulation
• Animals cells have an elaborate ____.
• -_________ fibers embedded in a network of ________________
• The _______ connect the ECM to the _______________.
11. The extracellular matrix (ECM)
• Function- Cell to cell communication and cell-cell contact
• Plant cells are perforated with ______________, channels allowing cysotol to pass between cells.
12. ____________________
Fig. 7.28 inset
Animal Cell Junctions
tightjunctions
adheringjunction
gapjunction
Animal have 3 main types of intercellular links:
• __________________ and Eubacteria
• DNA is NOT enclosed in ____________
• Generally the smallest, ___________ cells
• No _______________
Prokaryotic Cells
Prokaryotic Structure
DNA
pilus
flagellum
cytoplasm with ribosomes
capsulecell wall
plasma membrane