A&P CH 3: Cells

What is the key thing to remember about cells?

function dictates form

What are a couple main types of cells?

• nerve

• muscle

• RBC

• gland

• immune

Nerve cells

have long extensions that allow these cells to quickly transmit electrical impulses from 1 part of the body to another

Muscle cells

elongated, thread-like fibers can shorten to allow body parts to move

Red blood cells (RBC)

concave shape allows these cells to bend + squeeze through tiny blood vess

Gland cells

intracellular sacs store + release substances, such as hormones, enzymes, mucus, + sweat

Immune cells

can recognize + destroy foreign invaders

Important structures of the cell

• plasma membrane

• nucleus

• ER

• ribosomes

• golgi apparatus

• centrioles

• lysosomes

• mitochondria

• cytoskeleton

What are organelles?

fill the cytoplasm + perform specific tasks in metabolism

• includes ER, ribos, golgi app, lysosomes, centrioles, + mitochon

Plasma membrane def

the exterior boundary of the cell

• selectively permeable + regulates passage of substances in/out of cell

Nucleus def

the cells “control center” that contains a complete set of 46 chromosomes (cells genetic info)

Endoplasmic reticulum (ER)

a network of mebraneous canals d+ curving sacs t/o the cytoplasm

• smooth ER= makes carbs +lipids for PM

• rough ER= makes prots w ribos for golgi app

Ribosomes

granules of prot + RNA that manufacture prots + are scattered t/o the cytoplasm → some attached to rough ER

Golgi apparatus

preps prots + packages them for export to other parts of the body

Centrioles

bundles of microtubules that play a role in cell div

Lysosomes

membranous vesicles that contain enzymes that help break down prots the cell doesnt need

Mitochondria

double membrane bound organelle that converts org compounds into ATP

• enzyme inside cristae are used for this

Types of movement through the cell membrane

1. passive transport

• reqs no energy → w/ conc grad

• includes diffusion, osmosis, filtration, + facilitated diffusion

2. active transport

• reqs energy → against conc grad

• includes trans by pumps + vesicles

Diffusion

a pass trans mechanism that involves the move of particles from an area of high to low conc

Osmosis

a pass trans mechanism involving the diff of water from an area of greater conc of H2O to an area of lesser conc of H2O

What are the lvls of tonicity ?

1. isotonic= a sol w/ the same conc of solutes as that inside the cell

2. hypertonic= a sol w/ a higher conc of solutes as that insidet he cell → RBC shrivel

3. hypotonic= a sol w/ a lower conc of solutes as that inside the cell → RBC burst

Filtration

a transport process in which H2O + dissolved particles are forced across a membrane from an areaof high to low pressure

• for ex in the kidneys to remove waste products from the blood or nutrients to/from capillaries

Facilitated diffusion

a transport process involving diffusion of a substances through a channel prot

• moles move down the conc grad

The sodium-potassium pump

an example of active transport that is crucial to the reg of volume of fluid w/in cells, provides the electrical potential necessary for nervous system activity + helps in heat production

• most important pump in the body

Steps of a NA-K pump

1. 3 Na+ ions from inside cell funnel into receptor sites on a channel prot

2. fueled by ATP, the channel prot releases the Na+ ions into the extracellular fluid, causing them to move from a area of lower to higher conc

3. meanwhile, 2 K+ ions from the cell enter the same channel prot

4. the K+ ions are then released inside the cell, this keeps the conc of K+ higher and Na+ lower w/in the cell

Transport by vesicles

endocytosis= brings substances into the cell

exocytosis= uses vesicles to release substances out of the cell

Phagocytosis

cell eating

Pinocytosis

uses vesicles to release substances out of cell

DNA

• double stranded helix

• deoxyribose

• has thymine, cytosine, guanine, and adenine

• in nucleus

• provs info for building prots

RNA

• single strand

• ribose

• has uracil, cytosine, guanine, + adenine

• leaves nucleus

• messenger, transfer, + ribosomal RNA

Prot syn steps

transcription + translation

Transcription

1. DNA segment unwinds → helicase unzips DNA strand

2. RNA assembles complementary nucleotides → codons

3. nucleotides attach to form mRNA

4. mRNA seperates + moves out of the nucleus

Translation

the proc by which mRNA is decoded by ribos to assemble AAs into a spec prot

• 1 triplet (group of 3 mRNA nucleotides) code for 1 spec AA w/ the help of tRNA to build chain

What are the 4 steps of the cell cycle?

1. G1

2. S

3. G2

4. M

G1 phase

1st gap phase → accumulating mats + syn of components needed for DNA rep

S phase

synthesis phase → DNA rep

G2 phase

2nd gap phase → prep for mitosis

M phase

mitotic or mitosis → cell div

What are the 4 steps of mitosis?

1. prophase

2. metaphase

3. anaphase

4. telophase

Prophase

chromatin condenses into tight chroms + the mitotic spindle starts to form

Metaphase

chroms line up along the middle of the cell

Anaphase

sister chromatids are pulled apart toward opposite poles of the cell

Telophase

2 new nuclear envelopes form around the separated sets of chroms

What process do sex cells divide through?

meiosis instead of mitosis → only cells to do this