Chapter 4 Eukaryotes Flashcards
Eukaryotes have many unique features that distinguishes them from prokaryotes
- Cilia-hairs-movement, rare
- Membrane sterols-1 bacteria has
- Ribosome structure- larger and denser
- different RNA sequence
- Membrane bound organelles
- nucleus
- multiple
- nucleus
Structures external to cell
- tubulin in 9+2 array with mem. covering
- Flagella- sperm only
- larger
- function in cell motility
- long in relation to cell size- covered in membrane
- wave not rotate
- Cilia
- shorter, more numerous
- move cell and propel substances across cell
- same internal as flagella
- power and recovery stroke
Glycocalyx in Eukaryotes
- carbohydrate coating in animal cells
- surrounds and stabilizes plasma membrane
- active in cell-cell recognition-signaling, communication
- only in cells with no cell wall
- extracellular matrix
Animal and protozoa cell walls
- plants, fungi, algae
- cellulose, chitin,glucan, mannan, silica,calcium carbonate
- NO PTG
- Protozoa have no cell wall but some have a pellicle, inorganic material, surrounding the plasma membrane
Eukaryotic Plasma Membrane
- similar in function and structure to prokaryotes
- phospholipid bilayer embedded with proteins
-addition of carbohydrates and sterols (cholesterols,
ergosterols)
-cell signaling - cell recognition
- stability
- spacers
- phospholipid bilayer embedded with proteins
Membrane protein functions
- transport
- maintain cell integrity
- attachment of proteins to internal structures
- receptors for cell signaling
- proteins in outer layer
- receptors typically glycoproteins
- proteins in outer layer
- enzomatic functions
- stabilization, connections b/w cells
Transport across eukaryotic membrane
- no cell wall
- passive- simple and facilitated diffusion; osmosis
- active- active transport,endocytosis, exocytosis
Endocytosis
- bring in material from surrounding environment
- Pinocytosis- plas mem folds inward- fluid into cell
- Phagocytosis- engulf particles and bring into cell
Exocytosis
-releases contents into external environment
Cytoskeleton
- dynamic network of protein filaments (microtubules,actin filaments, and intermediate filaments)
- anchor organelles, structural support, shape alteration, movement
Centrosomes
- pair of centrioles and proteins found near the nucleus
- involved in the assembly of microtubules
microtubules - tubulin polymers
- hollow tubes; walls- 13 columns of tubulin molecules
- protein subunit- tubulin
- main functions- maintenance of cell shape
- cell motility
- chromosome movements in division
- organelle movements
Microfilaments - actin filaments
- 2 intertwined strands of actin
- protein subunits- actin
- main functions-
- maintenance of cell shape
- changes in cell shape
- muscle contractions
- cytoplasmic streaming
- cell motility
- cell division
Cytoplasmic streaming
movement of eukaryotic cytoplasm from one part of the cell to another- helps distribute nutrients and move the cell over a surface - expells wastes
Least common filaments in euks
intermediate filaments
Membrane-bound organelles
- compartmentalization
- allows for division of labor
- nucleus
- mitochondria and chloroplast
- endoplasmic reticulum
- golgi apparatus
- lysosome and peroxisomes
- some have double membrane
Nucleus
- nuclear envelope - membrane around
- double membrane with pores
- nucleolus -sites of RNA synthesis
- DNA typically in multiple pairs of linear chromosomes
- associated with histone proteins
sexual or asexual reproduction in _____ only
eukaryotes- mitosis and meiosis
Endoplamic reticulum
- membrane synthesis organelle
- network of flattened tubules(cisterns) continuous with nuclear membrane
- rough ER-ribosomes present
- site of protein synthesis
- smooth ER - no ribosomes
- site of lipid/fat synthesis
Ribosomes
-protein synthesis
- Eukary- 80s
-larger 60s and small 40s sub units
- membrane-bound; attached to ER and nuclear
membrane
- free in cytoplasm
-Pors- 70s
-in chloroplasts and mitochondria-contain own
ribosomes
Golgi Body
- complex apparatus
- curved cisterns
- not continuous
- modifies, packages,and secretes products of ER
- produces lysosomes and vacuoles
- receives, ID’s and processes them
made by the golgi
lysosomes, peroxisomes, vacuoles
Lysosomes are
- Formed in the Golgi
- membrane enclosed sac of digestive enzymes
- non specific- garbage disposal
apoptosis
- programmed cell death
- by golgi
peroxisomes are
- bag of enzymes
- oxidation of fatty acids; destroys water- specific actions
- formed by dividing perosiomes
- split in 1/2 to make more
Vacuoles are
- derived from golgi
- store nutrients
- Primary purpose
- sequester harmful substances
Vacuole contents are determined by
cell type
- plant - 1 large with water
- animal - smaller- energy reserves, sugar
Contractile Vacuoles are
single cell in fresh water
- holds water until full then pushes water out
Endomembrane System
Network of internal membranes involved in synthesis or storage
- ER
- cell membrane
- Golgi
Mitochondria are
- double membrane
-inner membrane is folded into cristae - site of cellular respiration; ATP production
- 70s ribosomes and circular DNA; divide independently
of cell
-self replicating
-binary fission
No animal can make _____, instead animals process ____.
energy
energy
Mitochondria are similar to _____, in that they have the same size ______ and same type of _______ DNA. They also replicate using _____ which is the same as well.
prokaryotes
ribosomes
circular
binary fission
Plastids are
- for synthesizing and storage
- 2 compartment sugars
- chloroplasts for photosynthesis
- found in algae and green plants
- contain chlorophyll pigment in the coin-like thylakoids
- have stacked thylakoids-grana
- 70s ribosomes and circular DNA; divide independently of cell
Where do prokaryotes carry out photosynthesis?
Cell membrane
Endosymbiotic Theory
Evolution from prokaryotes to eukaryotes
- a pro engulfed another pro and over time became dependent upon each other
- proof - inside the cell the mitochondria and plastids have same size ribosomes and same circular DNA
Sugars are broken in the mitochondria and then used for
- ATP to do work
- moving material back and forth across the membrane
