Cell Structure and Function Terms

cell

smallest unit of life

microscope

allows scientists to see and study cells and identify cell organelles

robert hooke

first to see cells and gave them their name

organelle

part of a cell that performs a job or function for the cell (acts like organs in the body)

cell theory

all things are made of cells

cell=basic unit of structure and function

all cells come form pre-existing cells

things that a cell has

cell membrane, cytoplasm, DNA, ribosome, cytoskeleton

cell membrane

layer of molecules that creates the outside of the cell

function: controls what enters and exits the cell

Cytoplasm

a jelly-like liquid that fills the inside of the cells

function: holds the organelles and space where many chemical reactions

DNA

the genetic material of a cell

function: controls what the cell does

ribosome

tiny organelle that does not have

a membrane

Function: make proteins (Protein = large molecule used for many things in cells- have nitrogen (N) in them)

Cytoskeleton

protein fibers (sticks) that act

like the bones of the cell

Functions:

Supports & shapes the cell

Provides strength

Helps the cell to move

Helps in cell division

Holds organelles in place

Prokaryotic Cells

No nucleus (does have

DNA)

No membrane-bound

organelles (not formed

by a membrane)

Only unicellular (single-

celled) organisms

Example = bacteria

Eukaryotic cells

Has a nucleus

Has membrane-bound

organelles (covered in a

skin-like layer)

Can be multicellular or

unicellular (single-

celled) organisms

Example = plant,

animal, & fungi cells

Eukaryotic cells are ___ than prokaryotic cells because ________

larger, organelles create rooms that allow the cell to perform different functions at the same time

Nucleus

protects dna

nuclear envelope

double membrane that makes nucleus

nuclear pores

holes in the nuclear envelope that move in and out of the nucleus

Nucleolus

dense area inside of the nucleus that makes ribosomes

rough ER

membrane folds that have ribosomes attached to them-> make proteins

Smooth ER

membrane folds that do not have ribosomes attached to them->makes lipids (fats and oils) and hormones and breaks down toxins (like blood and alcohol)

Golgi apparatus

closely layered stacks of membrane envelopes (look like a stack of pancakes) -> receives, modifies, sorts, and delivers proteins

vesicle

membrane bound sac (container) that moves materials around the cell

- Made from a pinched off part of a membrane

- Cells can change the number of vesicles they have

Mitochondria

bean shaped organelle with two membranes that breaks down food to release usable energy (ATP)

-inner membrane has many folds

has its own dna and ribosomes

centrosome

area of cytoplasm where parts of the cytoskeleton are made

centrioles

cylinder shaped organelles that are 90 degrees to each other

- found in the centrosome

- only found in animal cells

- function unknown but might help with cell division

vacuole

liquid filled membrane sac (larger than vesicle) that stores food, waste, and water

- animal cells have many small vacuoles

- plants have 1 large vacuole= central vacuole

central vacuole

The large vacuole in plant cells that

stores water, pigments, waste, & other materials

- takes up most of the space in the cell

lysosome

A membrane sac that has enzymes (special proteins) inside it that breaks down and recycles cell waste & invaders (like old & damaged cell parts, large food molecules,

disease causing bacteria)

- Mostly found in animal cells, but also in some

plant cells

flagella

tail like structure in some animal cells and prokaryotes that function for movement

cell wall

the thick outermost layer in plant cells that gives extra protection, support, and shape to the cell

- Fungi & bacteria also have cell walls, but they are made of different molecules

chloroplast

has two outer membranes and contains chlorophyll (green color)

-Has its own DNA & ribosomes

-Only found in plant cells

-Function: uses light to build sugars (food)

other name of cell membrane

plasma membrane

what does it mean that cell membrane is selectively permeable

that it only allows some things to cross the cell membrane

what is the cell membrane made of

phospholipid

what is a phospholipid

a molecule made of a phosphate group, a glycerol, and two fatty acids

what is the phospholipid bilayer

a double layer of phospholipids

middle membrane is nonpolar because the polar heads point outwards and the hydrophobic tails point inward

which molecules can move through the membrane easily on their own

small, nonpolar molecules

ex: CO2 and O2

which molecules cant move through the nonpolar middle

large, polar, charged molecules

ex: H2O and sugars

what can move each other easily

lipids bc’s it’s fluid-like (flexible)

what are embedded/stuck in the membrane

proteins, some move molecules across the membrane (transport proteins)

what is embedded in the membrane and keeps it fluid and flexible

cholesterol

what is the Fluid Mosaic Model

it describes the membranes structure and behavior (membrane is flexible and made of many different molecules).

passive transport

molecules move across the cell membrane without the cell using energy

active transport

the cell uses energy (ATP) to move molecules across the cell membrane

how do molecules move during passive transport

molecules move from areas of high concentration to low concentration (move down a concentration gradient)

concentration gradient

the difference in the amount of substance between two places

what is equilibrium in passive transport

molecules move until they reach equilibrium which is when molecules are evenly distributed on both sides of the cell membrane.

what are the 3 types of passive transport

diffusion, facilitated diffusion, and osmosis

what is diffusion

molecules move across the cell membrane on their own, also called simple diffusion

facilitated diffusion

molecules diffuse through protein channels in the cell membrane, the molecules have to use a channel and cant cross on their own because they are polar, charged, or too big

osmosis

the passive transport of water across the cell membrane

active transport

molecules move from an area of low concentration to high concentration, molecules move up (or against) their concentration gradient

what mode of cellular transport do cells use to maintain homeostasis (stable internal condition)

active transport

what is ideal homeostasis for cells

doesn’t always want to be equal with the environment. Cells want their pH, temperature, and concentrations of molecules to remain stable

what does active transport require the cell to use

ATP

what are the 3 different ways that they can use ATP

protein pumps, endocytosis, exocytosis

how do protein pumps work

they work like a lock and key system, each protein only moves certain molecules

what is endocytosis

the cell uses vesicles to move molecules into the cell, once inside the cell the vesicle can fuse with lysosomes to break down the materials

what is exocytosis

the cell uses vesicles to move molecules outside of the cell, once the vesicle fuses with the cell membrane the materials are released

what is osmosis

the diffusion of water across the cell membrane, a type of passive transport, is very important because water is very important to cells

what part of the cell is mostly made of water and shows why osmosis is important

cytoplasm

how does water move through the cell membrane

on it’s own or through special proteins called aquaporins

what are the 3 types of cell environments

hypertonic, hypotonic, isotonic

hypertonic environment

environment has lots of solutes and little water

the cell has lots of water and few solutes

water moves out of the cell

the cell shrinks

hypotonic

environment has a few solutes and lots of water

the cell has a lot of solutes and a little water

water moves into the cell

the cell swells and can eventually burst

isotonic

equal amounts of solutes and water in the cell and the environment

water moves in and out of the cell equally

the cell stays the same

what environment do animal cells want to be in

isotonic bcs hypotonic can cause cell to lyse (burst) and hypertonic can cause the cell to shrink

what environment do plant cells want to be in

hypotonic bcs the cell wall prevents the cell from bursting, the water entering the plant makes it firm and allows plants to stand upright so that they can receive sunlight