Exam 2 - study guide

What are we made of?

all organisms are made of cells

Eukaryotic cells

Protists, fungi, animal, plants

DNA in nucleus that is bounded by a membranous nuclear envelope

membrane bound organelles

cytoplasm in the region between plasma membrane and nucleus
(generally larger)

Prokaryotic cells

Bacteria and Archaea

No nucleus

DNA in unbound region called nucleoid

no membrane bound organelles

cytoplasm bound by the plasma membrane

all cells

plasma membrane

semifluid substance called cytosol

chromosomes (carry genes)

ribosomes

Plasma membrane

selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell

What is this (typical rod-shaped bacterium)

bacterial chromosome

Bacterial chromosome

to carry the genetic information for that species of bacteria

what is this (a typical rod-shaped bacterium)

fimbriae

Fimbriae

enable the bacteria to bind to specific receptor structures and thereby to colonise specific surfaces

what is this (a typical rod-shaped bacterium)

Nucleoid

nucleoid

regulates the growth, reproduction, and function of the cell

what is this (a typical rod-shaped bacterium)

Ribosome

ribosome

intercellular structure made of both RNA and protein, and it is the site of protein synthesis in the cell

what is this (a typical rod-shaped bacterium)

Plasma membrane

plasma membrane

provides protection for a cell

what is this (a typical rod-shaped bacterium)

cell wall

cell wall

surrounds the plasma membrane of plant cells and provides tensile strength and protection against mechanical and osmotic stress

what is this (a typical rod-shaped bacterium)

capsule

capsule

protecting bacteria from toxic compounds and desiccation and allowing them to adhere to surfaces and to escape the immune system of the host

what is this (a typical rod-shaped bacterium)

Flagella

flagella

microscopic hair-like structures involved in the locomotion of a cell

Smooth ER

lacks ribosomes

synthesizes lipids

metabolizes carbohydrates

detoxifies drugs and poisons

stores calcium ions

Endoplasmic reticulum (ER) biosynthetic factory

ER membrane is continuous with the nuclear envelope

there are two distinct regions of ER

Smooth and Rough

Rough ER

surface is studded with ribosomes

Has bound ribosomes, which secrete glycoproteins (proteins covalently bonded to carbohydrates)

distributes transport vesicles, proteins surrounded by membranes

is a membrane factor for the cell

Endomembrane system

Nuclear envelope

endoplasmic reticulum

golgi apparatus

lysosomes

vacuoles

plasma membrane

(components are either continuous or connected through transfer by vesicles)

nuclear envelope (endomembrane system)

separates the contents of the nucleus from the cytoplasm and provides the structural framework of the nucleus

endoplasmic reticulum (endomembrane system)

Accounts for more than half of the total membrane in many eukaryotic cells

continuous with nuclear envelope

two distinct regions: smooth ER and rough ER

golgi apparatus (endomembrane system)

consists of flattened membranous sacs called Cisternae

Functions:

1. modifies products of the ER

2. manufactures certain macromolecules

3. sorts and packages material into transport vesicles

lysosomes (endomembrane system)

a membranous sac of hydrolytic enzymes that can digest macromolecules

the enzymes can: hydrolyze proteins, fats, polysaccharides, and nucleic acids

work best the acidic environment inside the lysosome

vacuoles (endomembrane system)

large vesicles derived from the endoplasmic reticulum and golgi apparatus

certain vacuoles in plants and fungi carry out enzymatic hydrolysis like lysosomes

helps in storage of salts, minerals, pigments and proteins within the cell

plasma membrane (endomembrane system)

provides protection

phagocytosis

one cell engulfing another cell forming food vacuole

contractile vacuoles

pump excess water out of cell

central vacuoles

hold organic compounds and water

ribosome

bound to ER, free in cytosol

site of protein synthesis in cell

Ribosome

Top: large subunit

bottom: small subunit

Mitochondria

sites of cellular respiration

(metabolic process that uses oxygen to generate ATP)

Chloroplasts

sites of photosynthesis

(contain chlorophyll, enzymes, other photosynthesis molecules)

Mitochondria chloroplasts (and bacteria)

enveloped by a double membrane

contain free ribosomes and circular DNA molecules

grow and reproduce somewhat independently in cells

1 Mitochondrion

Outer membrane

2 Mitochondrion

intermembrane space

3 Mitochondrion

Free ribosomes in the mitochondrial matrix

4 mitochondrion

DNA

5 Mitochondrion

inner membrane
(creates intermembrane space and mitochondrial matrix)

6 Mitochondrion

Cristae

7 Mitochondrion

Matrix

1. Chloroplast

Ribosomes

2 Chloroplast

Stoma

3 Chloroplast

Inner and outer membranes

4 Chloroplast

Granum

5 Chloroplast

DNA

6 Chloroplast

Intermembrane space

7 Chloroplast

Thylakoid

thylakoid

membranous sacs, stacked to form granum

stoma

internal fluid

Cytoskeleton

network of fibers extending throughout cytoplasm

organizes cells structures and activities, anchoring many organelles (helps to support cell and maintain its shape)

interacts with motor proteins to provide mobility (vesicles can “walk” along tracks provided by it

3 types of fibers make up cytoskeleton

Microtubules - thickest

microfilaments - (actin filaments) thinnest

intermediate filaments - middle

Microtubules

hollow rods constructed from globular protein dimers called tubulin

Functions

1. shape and support cell

2. cell mobility (cilia or flagella)

3. guide movements of organelles

4. separate chromosomes during cell division

microtubules (tubulin polymers)

hollow tubes; wall consists of 13 columns of tubulin molecules

Microfilaments

thin solid rods, built from molecules of globular actin subunits (bundles make up intestinal cells)

structural role: bear tension, resisting pulling forces within cell

Function:

1. maintain cell shape

2. changes in cell shape

3. muscle contraction

4. cytoplasmic streaming in plants

5. cell mobility

6. division of animal cells

microfilaments (actin filaments)

two intertwined strands of actin each a polymer of actin subunits

Intermediate filaments

fibrous proteins supercoiled into thicker cables

Functions:

1. maintains cell shape

2. anchors nucleus and other organelles

3. formation of nuclear lamina

Intermediate filaments (keratin fibers)

Fibrous proteins supercoiled into thicker cables

(only animal cells have these)

Peroxisomes

specialized metabolic compartments bounded by a single membrane

produce hydrogen peroxide and convert it to water

motor protein

protein that can move with the help from ATP

centrosome

microtubules grow out from

cell wall

extracellular structure - made of cellulose fibers embedded in other polysaccharides and protein

cell wall layers

Primary cell wall: relatively thin and flexible

middle lamella: thin layer between primary walls of adjacent cells

secondary cell wall: (in some cells) added between plasma membrane and primary cell wall

cell junctions

neighboring cells in animal or plants - adhere, interact, and communicate through direct physical contact

intercellular junctions

plasmodesmata

tight junctions

desmosomes

gap junctions

plasmodesmata

channels that perforate plant cell walls

water and small solutes (sometimes proteins and RNA) pass from cell to cell

Junctions in animal cells

tight junctions

desmosomes

gap junctions

tight junctions

prevent fluid from moving across a layer of cell

desmosomes

mediate direct cell-cell contacts and provide anchorage sites for intermediate filaments important for the maintenance of tissue architecture

Gap junctions

aggregates of intercellular channels that permit direct cell–cell transfer of ions and small molecules

Extracellular matrix (ECM)

animal cells version of cell wall

made up of glycoproteins - collagen, proteoglycans, fibronectin

ECM proteins bind to integrins

integrins

receptor proteins in plasma membrane

1 extracellular matrix (ECM)

collagen

2 Extracellular matrix (ECM)

Fibronectin

3 Extracellular matrix (ECM)

plasma membrane

4 extracellular matrix (ECM)

A proteoglycan complex

5 extracellular matrix (ECM)

integrins

extracellular matrix (ECM)

cytoplasm

extracellular matrix (ECM)

micro-filaments

Plasma membrane

selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell

(general structure is double layer of phospholipids)

1 plasma membrane

phospholipid

2 plasma membrane

proteins

3 plasma membrane

Carbohydrate side chains

4 plasma membrane

hydrophilic region

5 plasma membrane

hydrophobic region

animal cell

flagellum

2 animal cell

centrosome

3 animal cell (Cytoskeleton )

1. microfilaments

2. intermediate filaments

3. microtubules

4 animal cell

microvilli

microvilli

digestion and absorption of intestinal contents by increasing surface area of cell

5 animal cell

peroxisome

6 animal cell

mitochondrion

7 animal cell

lysosome

8 animal cell

golgi apparatus

9 animal cell

ribosomes