H. Eukaryotic Cell Walls and Cytoplasmic Membranes

Cell walls

Cell membrane

Cell walls

Cell membrane

Under Eukaryotic Cell Walls and Cytoplasmic Membranes

all eukaryotes have cell membrane- plasmalemma (plants, algae)

Cell membrane;maintain fluidity

they contain steroid lipids (sterols), such as cholesterol in animal cells that help ___

Cell membrane;movement of material

controls the ___ into and out of the cell

Ribosomes, Cytoskeleton, Centrioles and Centrosome

3 Nonmembranous organelles

Ribosomes

free or attached to endoplasmic reticulum

Ribosomes;80S

larger than prokaryotic ribosomes (___) instead 70S

Ribosomes

- composed of 60S and 40S subunits

30s

Small sub unit

50s

Large subunit

50s and 30s

Complete 70s ribosome

Cytoskeleton

composed of network of fibers and tubules

Cytoskeleton; cytoplasmic streaming

- acts to anchor organelles, functions in ___ and in movement of organelles within the cytosol, enables contraction of the cell, moves the cell membrane during endocytosis and amoeboid action, and provides the basic shape of many cells

-

Cytoskeleton

made up of tubulin microtubules (also found in flagella, cilia and centrioles), thinner microfilaments composed of actin and intermediate filaments composed of various proteins

Microtubule

Turbulence, 25 nm

Microfilament

Actin subunit, 7nm

Intermediate filament

Protein subunits, 10 nm

Centrioles and Centrosome

present in certain kind of eukaryotic cells

Animal and some fungal cells

2 centrioles

centrosome

animal and some fungal cells contain 2 centrioles which lie at right angles to each other near the nucleus, in a region of the cytoplasm called

plants, algae, fungi, and prokaryotes

lack both

centrioles and centrosomes

Centrioles and Centrosome

composed of 9 triplets of microtubules arrange in a

way that resembles the “9+0” arrangement seen at

the base of eukaryotic flagella and cilia

play a role in mitosis (nuclear division) cytokinesis

(cell division) and in the formation of flagella and cilia

Nucleus, ER, Golgi apparatus, Lysosomes, Peroxisomes, Vesicle and Vacuole, Mitochondria, Chloroplast

Under membranous organelles

Nucleus

- spherical to ovoid; the largest organelle in the cell; some have single nucleus while others are multinucleated while still others lose their nuclei

Nucleus

the control center of the cell”

nucleoplasm

it’s semi-liquid matrix is called ___

which may have one or more nucleoli – a specialized regions where RNA is synthesized

Nucleus

also contains chromatin – a thread like mass of DNA associated with special proteins called histones which play a role in packaging nuclear DNA

chromatin

A threadlike mass of DNA

Histones

Play a role in packaging nuclear DNA

nuclear envelope

surrounding the nucleus is a double membrane called ___ - contains nuclear pores that function to control the import and export of substances

Endoplasmic Reticulum

function as a transport system

Smooth ER and rough ER

2 forms of ER

Smooth ER

plays a role in lipid synthesis as well as transport

rough ER

- studded with ribosomes; proteins produced here are inserted into the lumen (central canal) of rough ER and transported throughout the cell

Golgi Apparatus

- the shipping department of the cell; receives, produces and packages large molecules for export from the cell

secretory vesicles

- packages secretions in sacs is called ___, which then

fuse with the cell membrane before dumping their contents outside the

cell via exocytosis

Lysosomes

- found in animal cells, contain

catabolic enzymes that damage

the cell if they’re released from

their packaging into the cytosol

Lysosomes

it’s enzymes are used during

the self-destruction of old,

damaged and

diseased cells and to digest

nutrients that have been

phagocytized

Peroxisomes

- contain oxidase and catalase that degrade poisonous metabolic wastes (such as free radicals and hydrogen peroxide)

-

found in all eukaryotic cells but are specially prominent in the kidney and liver cells of mammals

Vesicle and Vacuole

- general terms of sacs; large vacuoles are found in plants and alga cells that store starch, lipids, and other substance in the center of the cell (central vacuole)

Mitochondria

- spherical to elongated structures fond in most eukaryotic cell; like nuclei, they have 2 membranes, each composed of a phospholipid bilayer

the inner membrane’s surface area is often called the “powerhouse of the cell” because their cristae produce most of ATP in the cell

Mitochondria

-

the interior matrix of the mitochondrion contains small “prokaryotic” 70S ribosomes and a circular molecule of DNA - which contains genes for some RNA molecules and for a few mitochondrial polypeptides that are manufactured by mitochondria ribosomes, however, most mitochondrial proteins are coded by nuclear DNA and synthesized by cytoplasmic ribosomes- semi- autonomous.

Chloroplasts

- light harvesting structures found in photosynthetic eukaryotes

Chloroplast

- like mitochondria and nucleus, chloroplast have 2 phospholipid bilayer membranes and DNA

-

Chloroplast

can also synthesized a few polypeptide with their own 70S ribosomes

photosynthetic lamellae

photosynthetic prokaryotes lack chloroplasts and instead have infoldings of their cell membrane called ___

Chloroplast

semi-autonomous