Biology Unit 2- Cells

Robert Hooke

first to observe "small chambers" in cork and call them cells.

- by looking at a thin piece of cork under the microscope, he discovered cells

Anton van Leeuwenhoek

made first simple microscope and discovered animalecules (bacteria) by scraping plaque off of his own teeth

Robert Brown

discovered the nucleus

Mattias Schleiden

concluded that all plants are made of cells

-botanist

Theodor Schwann

concluded that all animals are made of cells

-zoologist

cell theory

idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

Exceptions to the cell theory

viruses and where the first cell came from

prokaryotic cells

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea.

-smaller than eukaryotes

-only have bacteria, ribosomes, cytoskeleton, cytoplasm, and cell membrane.

Eukaryotic cells

Contain a nucleus and other organelles that are bound by membranes. In every other kingdom (plants, animals, protist, Fungus)

endosymbiotic theory

theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms.

Mitochondria have their own DNA

Chloroplasts have their own DNA.

Nucleus

Control center of the cell. Contains DNA.

nuclear envelope

layer of two membranes that surrounds the nucleus of a cell

-Outter membrane is continuous with the RER

-both are lipid bilayers

-nuclear pores regulate the exchange between cytoplasm and the nucleus of ribosomes, proteins, and RNA

Nucleolus

Found inside the nucleus and produces ribosomes.

-non membrane bound

-makes RNA, DNA, and proteins

Chomosomes

threadlike structure within nucleus that contains genetic info that is passed on from generations

-tightly coiled so that DNA can be transferred when cells multiply

Chromatin

Clusters of DNA, RNA, and proteins in the nucleus of a cell

-loosely coiled when cells are not multiplying

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

-made of cytosol (water)

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement

Microtubules

longest and thickest component of the cytoskeleton

-hollow protein cylinder made of alpha and beta tublin

-radiate outwards from an area near the nucleus called the centrosome

Microfilaments

Long, thin fibers that function in the movement and support of the cell

-made of two actin chains twisted around one another

-actin

-keeps cell shape, allows movement with contraction of actin fiber (muscles)

intermediate filaments

A component of the cytoskeleton that includes all filaments intermediate in size between microtubules and microfilaments

-provides strength and holds organelles

-made of lamin, vimentin, keratin

Rough Endoplasmic Reticulum (RER)

the region of the endoplasmic reticulum that is studded with ribosomes and engages in protein modification

-makes proteins that are transported from the ER in transport vesicles

-works with the golgi apparatus tp get new proteins tp their proper place in the cell

Smooth ER

That portion of the endoplasmic reticulum that is free of ribosomes.

-lipid synthesis, calcium ion storage, drug detoxification

-found in lungs of drug addict because it is responsible for drug detoxification

Ribosomes

Makes proteins

-made of ribosomial RNA

-not surrounded by a membrane

-made up of large and small subunits

-on the RER, nucleus, nuclear envelope, cytoplasm

Golgi apparatus

A system of membranes that modifies and packages proteins for export by the cell

-made up of 5-8 cup-shaped membrane covered discs called cristernae

-found close to the nucleus of the cell

-transports lipids too

-in both plants and animals

in plants, the golgi body has enzymes that synthesize some of the cell wall polysaccharides

Lysosomes

An organelle containing digestive enzymes

-a type of vesicle

-formed by the golgi body

-break down harmful cell products, waste materials, and cellular debris

Autolysis: when lysosomes break down dying cells

Mitochondria

membrane-bound organelle that converts fuel into energy that is available to the rest of the cell

-power plants of the cell

-they make ATP with glucose and oxygen.

-have their own DNA

-The number of mitochondria in a cell depends on how much energy the cell needs

Prokaryotes produce ATP on their cell membrane

-has two membranes

-Matrix: fluid in the mitochondria

cristae: folds in the inner membrane

Chloroplast

organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy, used for photosynthesis

-looks like tiny disk

-type of plastid

-fluid within is called stroma

-has two membranes

-has thylakoids

Thylakoid

A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy.

-arranged in stacks called grona

-inside there is an empty space called the thylakoid space

Centrioles

Cell organelle that aids in cell division in animal cells only

-arrange micro-spindles that pull chromosomes apart during mitosis in cellular division

Cilia

Hairlike projections that extend from the plasma membrane and are used for locomotion

-cilia on human lungs sweep mucus and foreign particles toward the mouth and nose

Flagella

whiplike tails found in one-celled organisms to aid in movement

Vacoules

Temporary storage compartments in cells,sometimes used to store waste.

-big in plant cells and store lots of water

-membrane bound

Vesicle

A membrane bound sac that contains materials involved in transport of the cell.

-has at least one membrane (lipid bilayer)

-made in the golgi, ER, or from parts of the cell membrane

-separated from the cytosol so they can be used for transport or for spaces for biochemical reactions

Peroxisomes

Contain oxidase enzymes that detoxify alcohol, hydrogen peroxide, and other harmful chemicals

-a type of vesicle

-self replicate by growing and then dividing

-common in liver and kidney cells that break down harmful substances

-named after hydrogen peroxide that is produced while breaking down organic compounds

-separated into water and oxygen

transport vesicles

A tiny membranous sac in a cell's cytoplasm carrying molecules produced by the cell.

cell wall

A rigid layer of nonliving material that surrounds the cells of plants and some other organisms.

-provides extra structure for the cell

cell membrane

A cell structure that controls which substances can enter or leave the cell.

-things let in and out include water, gases, steroids, glucose, ions.

Semipermeable

some substances can pass directly through the cell membrane by passive or active transport

phosopholipid bilayer

part of cell membrane, phospholipids are phosphate and fatty acid lipids, has two layers

-Heads are hydrophilic (water-loving) so they do not pass through the membrane

-tails are hydrophobic (water-hating) so they can pass through the membrane

-glucose, Na+, and K+ need special proteins in order to pass through

integral membrane proteins

firmly embedded in the membrane

-transport molecules across the membrane

-can move easily around the membrane

-can be cell receptors or transporters

-integral monotopic proteins are fully embedded but are only attached from one side

peripheral membrane proteins

one portion anchored in the membrane

-can easily be removed

-move around the membrane

-involved in cell signaling

-hydrophilic

ion channels

channel proteins that transport ions and make passages through the membrane, and into the cell for certain molecules

Carbohydrates

the starches and sugars present in foods, supplies energy to our body

-carbohydrate chains are on the outside of cell membranes attached to some of the proteins because they cannot pass through

-labels a cell's identity type

Cholesterol

A lipid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids.

-help the plasma membrane keep it's shape

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane

-shows proteins move in the membrane rather than staying still

Functions of cytoplasm

1. Suspend organelles

2. Push against the plasma membrane to keep cell's shape

3. Provide a site for biochemical reactions to take place

Chromoplasts

type of plastid that stores pigments that are responsible for the bright colors in fruit and flowers

Leucoplasts

Organelles that store starches or oils

-also makes fatty and amino acids

Henri Dutrochet

discovered osmosis

Rudolf Virchow

proposed that new cells are formed only from cells that already exist

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Osmosis

Diffusion of water through a selectively permeable membrane

Hypertonic

Having a higher concentration of solute than water in a solution, makes a cell shrink because water leaves the cell to have equilibrium with the sodium. (plasmolysis).

Hypotonic

Having a lower concentration of solute than water in a solution. Makes a cell bloat and animal cells burst

-plant cells have turgor pressure against the cell wall, so a hypotonic solution is actually good for them.

-Cytolysis

Isotonic

Having the same solute concentration as another solution.

facilitated diffusion

Movement of specific molecules across cell membranes through protein channels

channel proteins

acts like pores in a membrane to let proteins through

-helps water pass through the membrane (aquaporins)

gated channels

A protein channel in a cell membrane that opens or closes in response to a particular stimulus.

-used to transfer molecules or ions

carrier proteins

bind to molecules and change shape to shuttle them across the membrane

-transfers glucose

-is in both passive and active transport

passive transport

the movement of substances across a cell membrane without the use of energy by the cell

active transport

the movement of materials through a cell membrane using energy

Endocytosis

captures molecules from the outside of the cell membrane and brings them in

Exocytosis

Process by which a cell releases large amounts of material

Pincocytosis

the cell takes in small droplets of extracellular fluid within small vesicles

Phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells

sodium-potassium pump

a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell after a nerve cell sends signals

-for each ATP molecule, 3 sodium go out, and 2 potassium go back in

electrochemical gradient

combination of forces acting on an ion

-chemical (identifying an ion)

-electrical (charge of ion)

determines if a molecule will difuse

electron microscope

microscope that forms an image by focusing beams of electrons onto a specimen

SEM

scanning electron microscope

-3D, not as zoomed in

TEM

transmission electron microscope

-2D, zoomed in more

How does an electron microscope work?

It passes electrons, rather than light through the specimen and can give much better resolution

-the specimen must be coated in metal (gold), kills the cells or organism

positives of electron microscopes

Higher resolution, higher magnification

Negatives of electron microscopes

smaller FOV, smaller depth of field, more expensive, cannot see living cells, and requires special training

charged

likes water

not charged

dislikes water

gap junctions

connects two cells, leaves a gap so that material can be transfered

tight junctions

connects to cells, no gap

basal body

The structure of the neuron minus the axon

A protein structure that extends outwards from a cilium. It is anchored beneath the plasma membrane of the cilium.

Axon

the neuron extension that passes messages through its branches to other neurons or to muscles or glands

Nucleiod

A dense region of DNA in a prokaryotic cell. Does not have a nucleus

-clumped in the middle

Aquaporins

water channel proteins. pores in the membrane (channel proteins) that let water through

desemosomes

hold cells together, strong

Plasmodesmata

gaps in the cell wall containing cytoplasm that connects two cells

-gap junction for plants

receptor-mediated

signal to let molecules go through endocytosis.

-when something hits the receptor, it sends a signal to do endosytosis

turgor pressure

The pressure that water molecules exert against the cell wall

Aerobic

requires oxygen

Anerobic

no oxygen

Archaea

One of two prokaryotic domains, the other being Bacteria.

Chlorophyll

A green pigment found in the chloroplasts of plants, algae, and some bacteria

Contracle vacuole

The cell structure that collects extra water from the cytoplasm and then expels it from the cell

er

intracellular transport

food vacuole

small cavity in the cytoplasm of protists that temporarily stores food

Plastid

Organelles found in only plant cells.

They are surrounded by a double membrane and serve many functions.

Chromoplasts

Leucoplasts

RNA

A single-stranded nucleic acid that passes along genetic messages

Attatchment proteins

Proteins that anchor the cell membrane by various ways (such as binding the membrane to the cytoskeleton)

fluid

Any substance that can flow (includes gases)

Glycoproteins

a protein in which a carbohydrate is attached

Plasmolysis

Collapse of a walled cell's cytoplasm due to a lack of water

receptor proteins

a protein, located on a membrane ( or in the cytoplasm), that recognizes and binds to specific molecules. Binding by receptor proteins typically triggers a response by a cell such as endocytosis, increased metabolic rate, or cell division.

recongnition proteins

Dozens of types spread across cell's plasma membraneHas binding site for a specific molecule