Topic 2: The Cells and Its Functions

The different substances that make up the cell are collectively called

protoplasm

Protoplasm is composed mainly of five basic substance

water, electrolytes, proteins, lipids, and carbohydrates

Most cells, except for fat cells, are comprised mainly of water in a concentration of

70% to 85%

second most abundant substances in most cells, which normally constitute ________________.

protein

10% to 20% of the cell mass

2 types of protein

(1) Functional protein

(2) Structural protein

Structural proteins are present in the cell mainly in the form of _________ that are polymers of many individual protein molecules

long filaments (microtubules)

what proteins that are mainly the _______of the cell and are often mobile in the

cell fluid

Functional protein

enzyme

T or F: many of structural protein are adherent to membranous structures inside the cell and catalyze specific intracellular chemical reactions

F: should be functional

Important lipids that constitute about _____ of the total cell mass

phospholipids and cholesterol

2%

What is another name for triglycerides and what percent of the cell mass in an adipocytes does it account for?

neutral fats

95%

carbohydrates usually averages only about ___ of their total mass but increases to as much as ________ and _________.

1%

3% in muscle cells and, occasionally, to 6% in liver cells

insoluble polymer of glucose that can be depolymerized and used rapidly to supply the cell’s energy needs

glycogen

without mitochondria of the cell, how much of the cell’s energy would cease immediately?

95%

approximate composition of cell membrane

55% proteins, 25% phospholipids, 13% cholesterol, 4% other lipids, and 3% carbohydrates

plasma membrane thickness

7.5 to 10 nanometers

The basic lipid bilayer is composed of three main types of lipids

phospholipids, sphingolipids, and cholesterol

the most abundant cell membrane lipids

phsppholipids

T or F: in the middle of the lipid bilayer, fat-soluble

substances, such as oxygen, carbon dioxide, and alcohol, can

penetrate this portion of the membrane with ease

true

T or F: lipid layer in the middle of the membrane is permeable to the usual water-soluble substances, such as ions, glucose, and urea

F: impermeable

Sphingolipids, derived from the amino alcohol

sphingosine

mainly help determine the degree of permeability (or impermeability) of the bilayer to water-soluble constituents of body fluids

cholesterol

T or F: sphingolipids controls much of the fluidity of the membrane as well

F: cholesterol

proteins provide structural channels (or pores) through which water molecules and water-soluble substances, especially ions, can diffuse between extracellular and intracellular fluids

integral proteins

membrane proteins are mainly

glycoprotein

act as carrier proteins for transporting substances that otherwise could not penetrate the lipid bilayer

integral proteins

what carrier proteins even transport substances in the direction opposite to their

electrochemical gradients for diffusion

integral proteins

function almost entirely as enzymes or as controllers of transport of substances through cell membrane pores

peripheral proteins

about _____ of the membrane lipid molecules are glycolipids

one tenth

the membrane carbohydrates

glycocalyx

Membrane carbohydrates occur almost invariably in combination with proteins or lipids in the form of ____________

glycoproteins or glycolipids

gives most cells an overall negative surface charge that repels other negatively charged objects

glycocalyx

Dispersed in the cytoplasm are neutral ______, _______, _______, ________ and five especially important organelles—

neutral fat globules,glycogen granules, ribosomes, secretory vesicles

the endoplasmic reticulum, the Golgi apparatus, mitochondria, lysosomes, and peroxisomes

the network of tubular structures of the ER

cisternae

the ER of the liver cells, can be as much as _____ the cell membrane area

30 to 40 times

a watery medium that is different from fluid in the cytosol outside the endoplasmic reticulum

endoplasmic matrix

the space inside the endoplasmic reticulum is connected with

the space between the two membrane surfaces of the nuclear membrane

ribosomes are composed of a mixture of ________; they function to synthesize

new _________ molecules in the cell

RNA and proteins

protein

smooth ER functions for

synthesis of lipids

how are lysosomes formed?

by breaking off from the Golgi apparatus; they then disperse throughout the cytoplasm

The lysosomes provide an __________ that allows the cell to digest:

(1) damaged cellular structures

(2) food particles that have been ingested by the cell; and

(3) unwanted matter such as bacteria

length of lysosomes are usually

250 to 750 nanometers in diameter

_______ are surrounded by typical lipid bilayer membranes and are filled with large numbers of small granules,___________ in diameter, which are protein aggregates of as many as ______________

lysosomes

5 to 8 nanometers

40 different hydrolase (digestive) enzyme

Enzymes that are highly concentrated in the lysosomes

hydrolytic enzymes

What are hydrolytic enzyme?

enzymes capable of splitting an organic compound into two or more parts by combining hydrogen from a water molecule with one part of the compound and combining the hydroxyl portion of the water molecule with the other part of the compound

perixisomes are formed by

self-replication (or perhaps by budding off from the smooth endoplasmic reticulum)

rather than from the Golgi apparatus

Perixisomes contains what enzymes

oxidase

oxidase enzyme present in large quantities in peroxisomes, to oxidize many substances that might otherwise be poisonous to the cell

hydrogen peroxide (H2O2)

What organelle catabolize long-chain fatty acids

peroxisomes

alcohol that a person drinks is detoxified into ______ by the ______ of the liver cells

acetaldehyde

perixisomes

secretory substances are formed by the

endoplasmic reticulum–Golgi apparatus system

which part of the mitochondria are oxidative enzymes are attached

cristae

generally strong ropelike filaments that often work together with microtubules,

providing strength and support for the fragile tubulin structures

intermediate filaments

why intermediate filaments are named as such

their average diameter is between that of narrower actin microfilaments and wider myosin filaments found in muscle cells

T or F: Only limited cells have intermediate filaments

F: all cells

The _______ is a strong tubular structures, made form a special type of stiff filament composed of polymerized ________ molecules

microtubules

tubulin

the centrioles and mitotic spindles of cells undergoing mitosis are composed of

stiff microtubules

control and promote cell reproduction

gene

a membrane wherein two separate bilayer membranes, one inside the other

nuclear membrane aka nuclear envelope

the nuclear outer membrane is continuous with the ____ of the cell cytoplasm

endoplasmic reticulum

central area of each pore is only about ______ in diameter

9 nanometers

nuclear pores allow molecules up to a molecular weight of ______ to pass through with reasonable ease

44,000

organelle that does not have a limiting membrane

nucleolus

The nucleolus enlarges considerably when the cell is actively

synthesizing proteins

cell has a diameter about ___________ and therefore a volume about ___________

1000 times that of the smallest virus

1 billion times that of the smallest virus

The essential life-giving constituent of the small virus is a _________ embedded in a coat of protein

nucleic acid

size of pinocytic vesicle

100 to 200 nanometers in diameter

most large macromolecules such as proteins enter cells through

pinocytosis

a protein on the inner side of the membrane, forms a lattice or scaffold beneath coated pits

Clathrin

only _______ and ___________ are capable of phagocytosis

tissue macrophages and some white blood cells

intermediation of antibodies that attaches to the phagocyte receptors, dragging the bacterium along with it

opsonization

How phagocytosis occur in steps:

1. Receptors bind to particle ligands →

2. Membrane evaginates → surrounds particle in a zipper-like fashion →

3. Actin and contractile proteins encircle vesicle → push it inward →

4. Vesicle pinches off → free phagocytic vesicle forms inside the cell.

What do lysosome releases on the vesicle

acid hydrolase

the pinocytotic and phagocytic vesicles containing lysosomes can be called the ________ of the cells

digestive organs

entire digestion of the cell by the lysosome

autolysis

bactericidal agents that can kill phagocytized bacteria in lysosome

(1) lysozyme, which dissolves the bacterial cell wall;

(2) lysoferrin, which binds iron and other substances before they can promote bacterial growth; and

(3) acid at a pH of about 5.0, which activates the hydrolases and inactivates bacterial metabolic systems

“to eat one self”

autophagy

digestion of obsolete organelles and the nutrients are reused by the cell

autophagy

In liver cells, the average mitochondrion normally has a life span of only about _______ before it is destroyed

10 days

It provides a vast number of enzymes that are capable of detoxifying substances, such as drugs, that might damage the cell. It achieves detoxification by processes such as coagulation, oxidation, hydrolysis, and conjugation with glycuronic acid.

smooth ER

Golgi apparatus synthesize certain carbohydrates which are

hyaluronic acid and chondroitin sulfate

functions of hyaluronic acid and chondroitin sulfate in the body

(1) they are the major components of proteoglycans secreted in mucus and other glandular secretions;

(2) they are the major components of the ground substance, or nonfibrous components of the extracellular matrix, outside the cells in the interstitial spaces, which act as fillers between collagen fibers and cells;

(3) they are principal components of the organic matrix in both cartilage and bone; and

(4) they are important in many cell activities, including migration and proliferation.

newly formed protein molecules can be detected in the granular endoplasmic reticulum within

3- 5 mins

newly formed proteins are already present in the Golgi apparatus within

20 mins

the proteins are secreted from the surface of the cell within

1-2 hrs

Exocytosis, in most cases, is stimulated by

entry of calcium ions into the cell

highly metabolic and capable of forming new intracellular structures and secretory substances to be extruded from the cell

membranous system of the endoplasmic reticulum and Golgi apparatus

The principal substances from which cells extract energy are foods that react chemically with oxygen—

carbohydrates, fats, and proteins

all carbohydrates are converted into glucose by the ______ and _______ before they reach the other cells of the body

digestive tract and liver

glucose is converted by enzymes in the ______ into pyruvic acid (a process called glycolysis)

cytoplasm

glycolysis accounts for _______ of the overall energy metabolism of the cell

less than 5%

pyruvic acid derived from carbohydrates, fatty acids from lipids, and amino acids from proteins is converted into the compound ________ in _________

acetyl-coenzymeA (CoA)

the matrix of mitochondria

acetyl-CoA is split into its component parts, hydrogen atoms and carbon dioxide

citric acid cycle

the reaction during citric acid cycle that releases large amount of energy

when hydrogen combine with oxygen that has also diffused into the mitochondria.

the initial event during splitting of acetyl CoA to its component parts is

the removal of an electron from the hydrogen atom, converting it to a hydrogen ion

overall process for formation of ATP is called

chemiosmotic mechanism

cells—the renal tubular cells—use as much as _____ of the ATP that they form for this purpose alone

80%

a crawling-like movement of an entire cell in relation to its surroundings

Ameboid movement

example of Ameboid movement

• movement of white blood cells through tissues

• fibroblasts move into a damaged area to help repair the

  damage

• germinal cells of the skin

causes attachment of the pseudopodium to surrounding tissues so that it becomes

fixed in its leading position while the remainder of the cell body is being pulled forward toward the point of attachment

receptor proteins

The cilium moves forward with a sudden, rapid whiplike stroke ________ bending sharply where it projects from the surface of the cell

10 to 20 times per second