Cells pt1

Cells vary in ____ and ____

Size, shape

how many different proteins within cell

20,000

Mitochondria produce

billion ATP molecules

Cell description

basic unit of structure/function

measured in micrometers

human body made up of 37 trillion cells

body has 290 diff cells types

developed specialized characters= differential

3 major parts of cell

1. nucleus

2. cytoplasm

3. cell membrane

nucleus

amoung largest organelle, enclosed by double membrane, studded w opening (nuclear pores), has darkened region, nucleolus is where ribsomones are found

controls cell activities e.g homeostasis

cytoplasm

consists of organelles w specific function, suspended in a liquid (cytosol)-fluid portion of cytoplasm

contains skeleton (framework of protein rods and tubules)

organelles+ cytosol= cytoplasm

organelle

tiny solid structures w specific function in cell

cell membrane

“phospholipid bilayer”

function: keep toxins out, maintain integrity of cell, regulate entry, exit of substances, signal transduction ( permits cells to receive/respond to messages)

made up of: cholesterol, proteins, phospholipids

phospholipids

head/tails

hydrophobic tail ( made of fatty acids), hydrophilic head ( like dissolves like) top= extracellular bottom= intracelleur

lipids (fats/steroid hormones) can pass through easily, membrane is impermeable to h20 molecules e.g amino acids, sugars, proteins, nucleic acids, irons

use transmembrane act like channels (get proteins, irons, sugars through membrane)

fluid mosaic models

molecules move in/through bi-layer of cell membrane called mosiac because it appears non-random

faulty ion channels

lead to diseases

abnormal CI- channels

cystic fibrous (production= think mucus, difficulty breathing, clogged pancreas, salty sweat)

mutations in k+ channels

disrupt the electrical activities of heart and disturb heart rhythm

mutations in Na+ channels

inability to feel pain

cellular adhesive molecules (CAMS)

class of surface protein

guide cells on the move’

play roal in inflmmation

2 types:

selectins: coat white blood cells and anchor w friction

inteigrins: direct white blood cells w/ capillary walls towards infection sites

ribosomes

site of protein synthesis

free-floating in cells/attached to endoplasmic reticulum (ER)

composed of rRNA and proteins

endoplasmic reticulum (ER)

membrane-bound sacs (+ribsomes) canals, vesicles

tubular transport system, connected to Golgi

function: rough ER= protein synthesis (ribosomes) and transport Smooth ER= no ribosomes, conducts lipid synthesis

Golgi apparatus

structure: sacs of flattened membrane sac (5-8)

Location: outer to ER

function: ‘post office’ refines, packages, delivers proteins made on the rough ER

tags molecules so they can be delivered to appropriate places within cell/exported (exocytosis)

mitochondria

‘power house of cell’

structure: double membrane-bound fluid-filled sacs

function: house chemical reactions that extract energy from nutrients

(cellular respiration) produces ATP, makes adenosine triphosphate

lysosomes

‘garbage disposals’

small membranous sacs

dismantle debris, destroy worn-out parts, practice autography (eating oneself)

contains powerful enzymes that digest proteins, carbs, nucleic acids, and bacteria

peroxisomes

In eukaryotic cells, membranous sacs contain enzymes that digest lipids, alcohol, toxins 9liver, kidney cells)

chemical detoxification (involved in metabolism)

use catalyst to break down hydrogen peroxide to h20 and o2

function: contains lysozyme, degrades molecules, contain catalyst enzyme: convert/break down hydrogen peroxide to water and oxygen to neutralize toxicity

vesicles

store/transport substances substances, milk, gluclose

glucose enters cell (aids insulin receptor) gets transported into cel to mitochondria

microfilaments/microtubules/intermediate filaments

Thread-like structures in cytoplasm, create cytoskeleton

microfilaments: tiny rods of actin; provide cellular movement e.g, muscle contraction

microtubules: 2-3x larger diameter than MF, made of protein tubulin, aid in maintaining cell shape, more organelles, make up cilia, flagella, and centrioles

intermediate filaments: composed of lamins (several types of proteins) help support nuclear envelope, a cytoskeletal structure

centrosome

in cytoplasm near nucleus

“central body” consists of 2 centrioles (cylindrical,MT)

involved in the development of spindle fibers in cell division

produce spindle fibers, division and distribute chromosomes to performing daughter cells

cilia

extension of the cell membrane, from fringe on surface

consists of microtubules

shorter than flagella, abdunt when present

beat back and forth in coordinated manner

propel mucus in resp. tract, propel egg toward uterus

flagella

causes entire cell to move

tail of sperm is only flagellum in human body

movements in and out of cell

physical (passive) no ATP

physiological (active) needs ATP

physical (passive)

1. diffusion (gases in our lungs)

2. osmosis (lg. sm. intestine)

3. facilitated diffusion (glucose and amnio acid transport)

4. filteration (kidneys)

physiological (active)

1. active transport

2. endocytosis

3. exocytosis

4. transcytosis

diffusion

only works across extremely short distances

atoms, molecules, ions move from high to low concentrations due to constant motion of atoms, molecules, ions

equilibrium

reached when concentrations of h20 and solute are equal in both compartments

facilitated diffusion

across cell membrane through ion channels/transporter

h2o soluble substances: glucose amino acids, na+ cl- allow for lipid insoluble soulute stop pass through, allow diffusion and water

osmosis

movement of water across a selectively permeable membrane from region of high water concentration to low water concentration (like diffusion but water only)

hydrostatic pressure

pressure of water inside cell pushing on membrane

osmotic pressure

tendency of water to move into cell by osmosis (more solutes inside= high osmotic pressure)

osmotic pressure

isotonic: same osmotic pressure, cells in solution have no net/gain loss of water

hypertonic: high osmotic pressure, cells in solution loose water (shrink)

hypotonic: low osmotic pressure, cells in solution gain water (swell)

filteration

forces molécules through membranes by exerting pressure separate solids, size of particles e.g small solutes filtered in kidney lg. plasma proteins aren’t

active transport

movement of substance across membrane from region of low concentration against region of high concentration against concentration gradient e.g sugar, amino acids, na+ ions

ATP

provides energy to move molecules against concentration gradient

endocytosis

movement of substance into cell inside vesicle 3 types:

Pinocytosis: membrane engulfs droplets of liquids

phagocytosis: membrane engulfs solid particles

Receptor-mediated endocytosis: membrane engulfs specific substances, bound to receptor proteins on membrane

exocytosis

release substance/ particles from cell e.g release of neurons transmitters from nerve cell

vesticles containing particles fuse with cell membrane realease contents

transcytosis

quickly transports substances from 1 to another e.g gloclsoe, albumin