Cell Structure and Function

Question 1

plasma membrane structure and function

Answer 1

structure: phospholipid bilayer with embedded protiens,

primary function: protection and separation of intracellular components from extracellular environment

Question 2

nucleus structure and function

Answer 2

structure: gel like matrix,
function: controls and regulates the activities of the cell

Question 3

endoplasmic reticulum structure and function

Answer 3

structure: paired membranes and flat vesicles (canals) that connect nucleus to cytoplasm
function: The functions of the endoplasmic reticulum can be summarized as the synthesis and export of proteins and membrane lipids, calcium storage and release, mRNA is translated here to make protein of secretory cells like digestive enzymes and insulin

Question 4

ribosome structure and function

Answer 4

structure:
function: site of protein synthesis

Question 5

mitochondria structure and function

Answer 5

structure: tiny little bean in the cell
function: store energy as ATP and use ATP as energy for cellular activities with glucose a fuel, key regulator of apoptosis, has it’s own DNA and ribosomes

Question 6

lysosomes and peroxisome structure and function

Answer 6

structure:
L function: lysosomes are the stomach of the cell and have enzymes that clean up the cell by breaking up potentially harmful products and then split into ECF. They do this by AUTODIGESTION
P function: peroxisomes contain enzymes that degrade peroxides, free radicals, and can break down fatty acids if needed

Question 7

What are the three types of cell membrane receptors?

Answer 7

1. Ligand-gated ion receptor
2. G-protein linked receptor
3. Enzyme-linked receptors

Question 8

Describe the lock and key mechanisms of the ligand receptor

Answer 8

Enzymes are highly specific. They must bind to a specific substrate before they can catalyze a chemical reaction. In lock-and-key model, the enzyme-substrate interaction suggests that the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another.

Question 9

define the cytoskeleton and it’s filaments

Answer 9

microtubules: develop and maintain cell form, support structure for organelles.
microfilaments: produce muscle contraction
myosin filaments

Question 10

explain the importance of ATP for cells energy metabolism

Answer 10

ATP captures chemical energy obtained from the breakdown of food molecules and releases it to fuel other cellular processes. ATP is a special carrier for cellular energy

Question 11

compare glycolysis, Krebs cycle, and oxidative phosphorylation by location in cell and the amount of ATP produced

Answer 11

glycolysis: cytoplasm, ATP: 2 molecules
Krebs cycle: mitochondria, 34 ATP molecules
oxidative phosphorylation: 36 ATP molecules

Question 12

compare and contrast membrane transport mechanisms such as diffusion, osmosis, active transport, endocytosis and exocytosis.

Answer 12

passive diffusion: water, Co2, ethanol can cross membrane with no energy needed
active diffusion: movement from high to low concentrations facilitated by a transport proteins

osmosis: when a semipermeable membrane separates two fluid spaces, water will flow from an area of lower solute concentration to one of higher solute concentration to achieve equilibrium so that the osmotic pressures are balanced.

active transport: requires energy for the transport of substances, ions are pumped against a concentration gradient (Na/K+ ase pump), energy comes from ATP splitting by enzyme ATPase.

endocytosis: Endocytosis occurs when a portion of the cell membrane folds in on itself, encircling extracellular fluid and various molecules or microorganisms. The resulting vesicle breaks off and is transported within the cell.
exocytosis: secretion of intracellular substances into extracellular space, opening in cell membrane allows for the release of substances.

Question 13

explain how the sodium potassium pump works as an active transport mechanism and the role of ATP

Answer 13

• the pump pumps ions against a concentration gradient in order to move substances across the membrane.
• ATP provides the energy for the sodium and calcium to move across and transport the substances

Question 14

describe the process of diffusion, osmosis, facilitated diffusion and active transport in the movement of particles and ions. Which requires energy?

Answer 14

simple diffusion: movement from high to low
osmosis: movement from low to high with a semi-permeable membrane.
facilitated diffusion: diffusion helped by a transport protien, ENERGY
active transport: ENERGY, ions are pumped against a concentration gradient (Na/K+ pump)

Question 15

describe action potential and the role of the resting membrane potential RMP

Answer 15

an action potential is rapid changes in the membrane potential at voltage gated channels. This sudden change from a negative RMP to threshold causes and opening of the membrane channels. This allows large amounts of Na + ions to enter cells causing depolarization, then Na+ channels close and potassium exits cell and returns to RMP.
When RMP is above threshold, an action potential happens.

Question 16

what are the general structures and function of the four main tissue groups?

Answer 16

Epithelial tissue forms sheets that function to cover the body’s surface, line internal surfaces, form glandular tissue. Structures: simple, stratified, pseudostratified Function: covering and protection

Muscle tissue: 
structure: striated
function is contraction, types: cardiac muscle, smooth muscle, skeletal muscle

connective tissue:
Connective tissue is classified into two subtypes: soft and specialized connective tissue. Major functions of connective tissue include: 1) binding and supporting, 2) protecting, 3) insulating, 4) storing reserve fuel, and 5) transporting substances within the body.

nervous tissue: Nervous tissue is found in the brain, spinal cord, and nerves. It is responsible for coordinating and controlling many body activities. It stimulates muscle contraction, creates an awareness of the environment, and plays a major role in emotions, memory, and reasoning.

Question 17

explain the process of skeletal muscle contraction

Answer 17

1. . Muscle activation: The motor nerve stimulates an action potential (impulse) to pass down a neuron to the neuromuscular junction. This stimulates the sarcoplasmic reticulum to release calcium into the muscle cell.
2. Muscle contraction: Calcium floods into the muscle cell binding with troponin allowing actin and myosin to bind. Calcium binds to troponin and moves tropomyosin so that myosin can bind to actin. Contraction then occurs.

Question 18

define cell adaptation

Answer 18

cells adapt to changes in their environment
ex: atrophy, hypertrophy, hyperplasia, metaplasia

Not always good adaptations

Question 19

describe cell changes that occur with atrophy, hypertrophy, hyperplasia, metaplasIa, dysPlasia, and give examples of each.
example demarcated by **

Answer 19

atrophy: decrease in cell size. disuse= **decreased skeletal muscle use.
hypertrophy: increase in cell size, **physiologic=exercise, cardiac=hypertension
hyperplasia: increase of cells in organ or tissue. Cells are capable of mitotic division, in the epidermis, intestinal epithelium, and gland tissue. **uterus, BPH, regeneration of Liver
metaplasia: one adult cell replaced by another type of cell, occurs in response to chronic Irritation and Inflammation **??
dysPlasia: deranged cell growth Producing cells that vary in size, shape and organization. Precursor of cancer. **cervical cells

Question 20

describe the mechanism whereby physical agents like blunt trauma, electrical forces, and temperature extremes produce cell injury

Answer 20

blunt trauma leaves bruising and tearing of muscles and cells.
electrical forces can kill cells, as can temperature extremes because of getting out of homeostasis.

Question 21

differentiate between the effects of ionizing and nonionizing radiation in terms of their ability to cause cell injury.

Answer 21

ionizing radiation has a shorter wavelength and can cause more cell injury because of it’s ability to destroy healthy cells.
non ionizing radiation is still somewhat toxic, but it does not cause cell death, only tissue damage. There is non-ionizing radiation in microwaves and etc.

Question 22

Relate free radical formation and oxidative stress to cell injury and death

Answer 22

free radical formation is when an atom has an unpaired valence electron. Free radical injury disrupts and damages cells and tissues. This can lead to cell injury and death

oxidative stress is when reactive oxygen species are no neutralized by the body. this can cause endothelial dysfunction with heart disease (closing of arteries), and also is found with cancer.

Question 23

explain the process of hypoxic cell injury and how it can be reversed.

Answer 23

hypoxic cell injury happens when there is inadequate amount of O2 in the air, Respiratory disease, ischemia anemia, edema, or inability of the cell to use oxygen as in sepsis.
the injury interrupts oxidative metabolism and generation of ATP. The cell then switches over to anaerobic metabolism. The sodium potassium pump fails and water accumulates in the cell.

TO REVERSE: get rid of the adverse influences on the cells homeostasis (give O2)

Question 24

Irreversible cell injury: necrosis and apoptosis

Answer 24

apoptosis is programmed cell death and so the cells are injured and weak already and it’s okay if they die and get recycled under normal conditions.

necrosis is an inflammatory process that interferes with cell replacement and tissue regeneration. necrosis can be recognized by gangrene on the extremities.

Question 25

what normal physiological and pathologic processes are affected by apoptosis

Answer 25

pathologic: carcinogenesis, neurodegenerative disease
normal: when cells die that need to die.

Question 26

what are the usual physiologic changes of aging and how are these changes differentiated from disease?

Answer 26

aging genes, telomere shortening, etc. ASK

Question 27

define telomeres and explain their role in aging

Answer 27

Telomeres are repetitive nucleotide sequences at each end of chromosomes. Their function is to protect the ends of the chromosomes from deterioration or fusion to other chromosomes during cell division. With every cell division, telomeres shorten.

Cells divide as one ages, and so the person is more exposed to disorders.

Question 28

how is genetic information stored in the cell and transported to the daughters cells during replication?

Answer 28

genetic information is stored in the cell neucleus. the information is transported to the cell through mitosis

Question 29

how does the simple 4 base structure of DNA serve as a template for synthesis of proteins that may contains 20 varieties of amino acids?

Answer 29

because many amino acids have the same first two letters.

Question 30

distinguish gene from genome, and

gene from allele

Answer 30

gene: The basic unit of heredity that occupies a specific location on a chromosome.
genome: the complete set of genes or genetic material present in a cell or organism. ALL genetic information

gene: The basic unit of heredity that occupies a specific location on a chromosome.
allelle: An allele is one of two or more versions of a gene. An individual inherits two alleles for each gene, one from each parent.

Question 31

differentiate the general steps in transcription vs translation

Answer 31

transcription: initiation, elongation, and termination.
translation: mRNA contacts and passes through ribosome and binds to RNA. then reads directions for protien synthesis, as mRNA passes through the ribosome, tRNA delivers the appropriate amino acid for attachment to the growing polypeptide chain with becomes the protien.

Question 32

what role do genes play in determining cell structure and function?

Answer 32

Genes encode proteins and proteins dictate cell function. Therefore, the thousands of genes expressed in a particular cell determine what that cell can do.

Question 33

by what mechanisms can the cells of an organism, which all contains identical genes, become differentiated into different cell types?

Answer 33

gene expression, or the degree to which a gene or particular group of genes is actively being transcribed.
induction or gene repression makes a trait less or more likely to pop up.