CHAPTER 3 CHAPTER 3 CELLS AND TISSUES CELLS AND TISSUES PART 1 – CELLS PART 2 - TISSUES.
Cells… part II
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Transcript of Cells… part II
Cells… part II
Converting Energy Mitochondria convert sugars
and fats to NRG (ATP) with the help of oxygen – Cellular respiration
Chloroplasts convert sunlight (solar NRG) to chemical NRG– Photosynthesis
Both have:– 2 membranes– Their own DNA and ribosomes– Ability to grow and reproduce
independently of the cell
Mitochondria• quantity in cell correlated with
metabolic activity•location of cellular respiration•double phoshoplipid membranes
w/ imbedded proteins- infoldings = cristae- space inside folds = matrix (contains enzymes, DNA, etc)- intermembrane space between cristae and smooth outer membrane
Chloroplasts•type of plastid
- contain pigments and used for storage in plants- amyloplasts store starch, chromoplasts store orange pigments, etc.
•thylakoids (flattened disks) and grana (stacked thylakoids) •stroma (fluid surrounding thylakoids)- contains enzymes,
DNA, etc.
Peroxisomes Single membrane Don’t bud from endomembrane
system like lysosomes Metabolism of fatty acids;
detoxification of alcohol (liver) Creates H2O2 as a byproduct of
detoxification Hydrogen peroxide then
converted to water and oxygen by enzymes
The Cytoskeleton Fibrous network in
cytoplasm– Support for organelles– Cell motility through
interaction w/ motor proteins
– Biochemical regulation- sending of mechanical signals
Components of the Cytoskeleton Microtubules:
•thickest•tubulin protein•shape, support, transport, chromosome separation• centrosomes, centrioles, cilia, and flagella
Microfilaments :•thinnest;•actin protein filaments; •motility, cell division, shape•includes actin and myosin
Intermediate filaments:•middle diameter•keratin;
•shape, nucleus
anchorage• nuclear lamina
and cell framework
Centrosomes/centrioles Type of microtubule Centrosome: region near nucleus Centrioles: 9 sets of triplet microtubules in a ring;
used in cell replication; only in animal cells
Cilia/flagella Locomotive appendages Ultrastructure: “9+2”
•9 doublets of microtubules in a ring •2 single microtubules in center •connected by radial spokes
anchored to a cell by basal body
Move using dynein protein
Dynein “walking”
Responsible for movement of cilia and flagella
Arms of microtubules “walk” along the adjacent ones, causing a wave-like motion
Microfilament Movement
Thin strands of actin and thicker strands of myosin allow:
Muscles to contract Amoebas to move w/
pseudopodia Cytoplasm to
“stream” in plant cells
Cell Wall Only in plant cells primary cell wall produced first middle lamella of pectin
(polysaccharide) forms later– holds cells together
some plants have a secondary cell wall– strong durable matrix– wood – between plasma membrane and
primary wall
Extracellular matrix (ECM) Glycoproteins
– proteins covalently bonded to carbohydrate
Collagen – 50% of protein in human body– embedded in proteoglycan
(another glycoprotein-95% carbohydrate)
Fibronectins – bind to receptor proteins in
plasma membrane called integrins
– cell communication
Intracellular JunctionsPLANTS: Plasmodesmata: cell wall
perforations; water and solute passage in plants
ANIMALS: Tight junctions~ fusion of
neighboring cells; prevents leakage between cells
Desmosomes~ riveted, anchoring junction; strong sheets of cells
Gap junctions~ cytoplasmic channels; allows passage of materials or current between cells