bio chapter 4

Cell theory

1. Cells are fundamentally units of life

2. All living organisms are composed of cells

3. All cells come from preexisting cells

Everything inside a cell except for the nucleus I those cells that have one is termed

Cytoplasm

Cytoplasm

Is water, along with thousands of substances that differ in identity and concentration from the composition of the outside of the cell.

Cell membrane

Performs the vital role of keeping the internal chemicals of a cell which carry out life’s functions, different from the chemical composition outside of the cell.

Fluid mosaic model

Random movements (fluid) and separatrness of the proteins and lipids (mosaic)

Phospholipids

The major lipid componet of biological membranes.

Phospholipids form thin bilayers

About 8 nanometer thick, with their charged, hydrophillic phospholipids “heads” on the external surfaces

is the simplest structural unit of a living

organism

cell

What are the 3 components of cell theory?

1. 1. Cells are the fundamental units of life

2. 2. All living organisms are composed of cells

3. 3. All cells come from preexisting cells.

Which statement is one of the tenets of cell theory?

a. All cells take in energy and matter from the

environment.

b. Cells are separated from their environment by a cell

membrane.

c. All cells come from preexisting cells.

d. All cells contain mitochondria.

e. Cells sustain the living state through chemical

transformations.

c

A general function of all cellular membranes is to

a. regulate which materials can enter or leave the cell.

b. support the cell and determine its shape.

c. produce energy for the cell.

d. produce proteins for the cell.

e. move the cell.

a

The cytosol and _______ are two components of the

cytoplasm in a prokaryotic cell.

a. Golgi apparatus

b. chloroplasts

c. mitochondria

d. ribosomes

e. smooth ER

D

What is the fluid mosaic model of cell membranes?

Lipids and proteins move laterally though the membrane.

Phospholipids form

bilayers

Phospholipids form bilayers with the charged,

hydrophilic “heads” of the phospholipid bilayer are on the ___ of the membrane

outside

The nonpolar hydrophobic fatty acid “tails” of the phospholipid bilayer are on the ___of the membrane

inside.

The hydrophobic interior prevents

molecules and ions through the membrane.

A general function of all cellular membranes is to

a. regulate which materials can enter or leave the cell.

b. support the cell and determine its shape.

c. produce energy for the cell.

d. produce proteins for the cell.

e. move the cell.

A section of the cell membrane is shown below. Which

letter(s) in the figure represent transmembrane proteins?

a. a and b

b. b and c

c. c and e

d. b, only

e. d and e

Membrane fluidity is influenced by:

• Lipid composition—short, unsaturated chains

increase fluidity; cholesterol alters interactions

among fatty acid side chains

• Temperature—fluidity decreases in cold

conditions; some organisms alter lipid

composition in cold environments

Membranes differ in lipid composition by

phospholipids vary in terms of fatty acid chain

length, degree of saturation, and polar groups.

at least partly

embedded in phospholipid bilayer. Hydrophobic

regions interact with membrane interior;

hydrophilic regions interact with the aqueous

environment.

integral membrane proteins

covalently

attached to fatty acids or other lipid groups

Anchored membrane proteins

no hydrophobic

groups; not embedded in the bilayer—polar or

charged regions interact with exposed parts of

integral membrane proteins or with charged

heads of phospholipids.

Peripheral membrane proteins

extend through the

bilayer; they may have domains with different

functions on the inner and outer sides of the

membrane

Transmembrane proteins

carbohydrate attached to a lipid

Glycolipid

oligosaccharide attached to a

protein

Glycoprotein

many carbohydrates attached

to a protein

Proteoglycan

Which compounds in a biological membrane form a barrier

to the movement of hydrophilic materials across the

membrane?

a. Integral membrane proteins

b. Carbohydrates

c. Lipids

d. Amino acids

e. Peripheral membrane proteins

biological membranes

allow some substances, but not others, to pass

Selective permeability

does not require energy;

substances diffuse down a concentration

gradient

Passive transport

requires energy and the

assistance of specialized membrane proteins.

Active transport

random movement of particles toward a state of equilibrium; a net movement from regions of higher concentration to regions of lower concentration

Diffusion

Diffusion in water is slow; speed depends on:

• Diameter of molecules

• Temperature

• Concentration gradient

• Area and distance

Simple diffusion

net movement of water from a region

of lower solute concentration to a region of

higher solute concentration

osmosis

pressure that must be applied to a solution to prevent flow of water

across a membrane by osmosis:

= CRT

osmotic pressure

solute particles per liter of water

(solute concentration)

Osmotic pressure can be quantified by

osmolarity

relative concentration of solutes on either

side of a membrane; determines direction and extent of net water movement

tonicity

The main components of biological membranes are

cholesterol and polar water molecules.

monosaccharides and polysaccharides.

lipids, proteins, and carbohydrates.

enzymes, electron acceptors, and electron donors.

nucleotides and nucleosides.

lipids, proteins, and carbohydrates.

When completed, the figure will illustrate secondary active transport. The small red circles represent the molecules being transported, and the H⁺ symbols represent hydrogen ions. The natural concentration gradient of the red molecules is shown. The hydrogen ion gradient was established by a membrane protein that is not shown. Given this information, which symbol should appear in the oval to indicate the direction of movement of hydrogen ions and red molecules?

Which is a correct pairing of a substance and the process by which it is transported across cell membranes?

Water by secondary active transport

Cholesterol by pinocytosis

A solution by receptor-mediated endocytosis

Pancreatic digestive enzymes by exocytosis

Glucose by phagocytosis

Pancreatic digestive enzymes by exocytosis

Cell A	1.0 µm
Cell B	2.0 µm
Cell C	3.0 µm

How do the surface area-to-volume ratios compare for the cells listed in the table, and which cell will have the most rapid transport of materials into its interior? Assume the cells are spherical.

The surface area-to-volume ratios increase from C to B to A, with cell A having the most rapid transport.

The surface area-to-volume ratios increase from A to B to C, with cell A having the most rapid transport.

The surface area-to-volume ratios increase from C to B to A, with cell C having the most rapid transport.

The surface area-to-volume ratios increase from A to B to C, with cell B having the most rapid transport.

The surface area-to-volume ratios increase from A to B to C, with cell C having the most rapid transport.

The surface area-to-volume ratios increase from C to B to A, with cell A having the most rapid transport.

Refer to the table. Bean seeds were analyzed at various times before and during germination. At each time of analysis, the total protein content was determined as well as the protein content corresponding to glyoxysome enzymes. These values were then expressed as percentages, as shown in the table.

Condition	% of total protein corresponding to glyoxysomal enzymes
Dry seed	2
Seed exposed to moisture	7
After 1 day	8
After 2 days	9
After 3 days	14
After 4 days	15
After 5 days	17
After 6 days	9

What do the results indicate about glyoxysomes and plant development?

Stored lipids in the seed are processed by glyoxysomes to supply chemical energy mainly for developing bean seedlings.

Refer to the table. The fatty acid composition of the intestinal cell membranes from three fish species were analyzed. One species lives in frigid Antarctic Ocean waters, another in the milder north Atlantic, and the third in the warm Mediterranean Sea.

Species	Saturated fatty acids	Monounsaturated fatty acids	Polyunsaturated fatty acids
1	35%	35%	30%
2	38%	35%	27%
3	26%	36%	38%

Use the data to match each species with its native waters.

Species 1: Antarctic; Species 2: Mediterranean; Species 3: north Atlantic

Species 1: north Atlantic; Species 2: Mediterranean; Species 3: Antarctic

Species 1: Mediterranean; Species 2: north Atlantic; Species 3: Antarctic

Species 1: north Atlantic; Species 2: Antarctic; Species 3: Mediterranean

Species 1: Mediterranean; Species 2: Antarctic; Species 3: north Atlantic

Species 1: north Atlantic; Species 2: Mediterranean; Species 3: Antarctic

The sodium–glucose co-transporter uses the _____________ of sodium ions down its concentration gradient causing _____________ to move glucose up its concentration gradient.

diffusion; active transport

An important difference between phagocytosis and receptor-mediated endocytosis is that

phagocytosis involves engulfment of larger substances, including whole cells.

Scientists have observed that in prokaryotes, translation of messenger RNAs begins before transcription has completed. In contrast, translation is completely separate from transcription in eukaryotes because DNA is isolated in the nucleus away from ribosomes, which carry out protein synthesis in the cytoplasm. What advantage does this compartmentalization provide eukaryotes?

It allows more opportunities for regulating gene expression.

Refer to the table. A student observed three single-celled organisms under a microscope and catalogued their features, as shown in the table.

	Cell membrane	Cell wall	Flagellum	Photosynthetic	Mitochondria	Ribosomes
Organism A	Yes	Yes	No	No	Yes	Yes
Organism B	Yes	No	No	Yes	No	Yes
Organism C	Yes	No	Yes	No	No	No

She concluded that all three were prokaryotes. Study the information that she recorded. Which organism or organisms should be reevaluated and/or reassigned?

Organisms A and C