Cellular Life

Sophomore Biology

Anton van Leeuwenhoek

-first to observe living microorganisms

-he discovered microorganisms (algae and alittle animals)

Robert Hooke

-first to use the term “cell”

Mattias Schleiden

-said that all plants are made of living cells

Theodor Schwann

-said that all animals are made of cells

Rudolph Virchow

-said that all cells come from living cells

Cell Theory

-all living things are made up of cells

-cells are the basic units of structure and function in living things

-new cells are produced from existing cells

All cells have:

-Plasma (cell) membrane

-Cytoplasm

-DNA

Prokaryotes

-do not have a nucleus

-smaller

-simpler, believed to be the first on earth

Eukaryotes

-have a nucleus

-larger

-most contain organelles

Bacteria and plant cells have:

a cell wall!

Unicellular Organisms

-live independently

ex. protists, a eukaryotic cell

Colonial Organisms

-collection of identical organisms that live together as a group

ex. e.coli

Multicellular Organisms

-collection of specialized cells that operate together to form a complex organism

-this may include tissues, organs and organ systems

The Hierarchy of Organization

(smallest)

1. atoms

2. molecules

3. organelles

4. cells

5. organisms

(largest)

Nucleus

-contains all of the cell’s DNA

-contains coded instructions for making proteins and other important molecules

-controls the majority of cell processes

DNA

-nucleic acid that holds hereditary info

-there is chromatin ( a loose form of DNA)

-there is chromosomes (a condensed form of DNA)

Nucleolus

-the dark are that contains RNA

-where ribosomes are made

Nuclear Envelope

-a double membrane (2 bilayers of phospholipids)

-it has pores that let RNA move out (not DNA)

Ribosomes

-form the chain of amino acids

-responsible for the primary structure of the protein

Two subunits: a large and small one

-Located in cytoplasm and on RER

Note: Viruses do not have ribosomes, but bacteria does

Endoplasmic Reticulum

-transport system within a cell

-composed of a network of flattened sacs

RER

-makes and transports tertiary and quartenary protein structures

SER

-makes lipids

-stores calcium

Golgi Apparatus

-proteins are carried to the golgi in vesicles

sorts and packages vesicles

made of: flattened membranous sacs

-attaches carbs to lipids and proteins

Vesicles

-tiny sacs that transport materials within or outside the cell.

-there are several different types

Vacuoles

-regulates water balance within a cell

Note: plant cells generally have large central vacuoles

-the size of a vacuole depends on the water availability

Lysosomes

-break down lipids, carbs, and proteins into small molecules that can be used by the rest of the cell

-they are also involved in breaking down organelles that have outliced their usefulness

Cytoskeleton

-extensive network of filaments in the cytoplasm of a cell

Made of: microfilaments and microtubules

Microfilaments

-form extensive networks

-produce a tough, flexible framework, helping cells move

Microtubules

-act like a highway in the cell

-moves materials and organelles to the appropriate locations

Centrioles

-paired barrel-shaped organelles

-located in the cytopalsm of animal cells near the nuclear envelope

-they are made of microtubules

-not found in plant cells

-aalways in pairs

Chloroplasts

-capture energyfrom sunlight and convert it into food that contains chemical energy

Mitochondria

-convert chemical energy from food into ATP in the presence of oxygen

-this process is called cellular respiration

Plasma Membrane

-made of phopholipids, cholesterols and proteins

-separates internal metabolic interations

-removes waste

-selectively lets molecules in and out

Passive Transport

-no ATP incolved

-moves from high to low concentration

-involves the movement of molecules across the cell membrane without an input of energy by the cell

Diffusion

-the movement of molecules from an area of higher concentration to lower concentration

-occurs until equilibrium is reached

-does not need a cell membrane to occur since cell membranes are build around lipids, the molecules that pass through are small and non-polar

-only hydrophobic molecules can pass through the cell membrane

Concentration

-the number of molecules in a volume of a substance

Concentration Gradient

-the difference in the concentration of molecules across a distance

Equilibrium

-when the concentration of molecules is the same throughout the space molecules occupy

Facilitated Diffusion

-the passive movement of molecules across the cell membrane via the aid of a membrane protein

-can be done with carriers or channels

Carrier

-integral proteins which bind a solute and undergo a conformational change to carry the solute across the membrane

ex.glucose

Channel

-integral proteins which contain a pore via which ions may cross from one side of the membrane to the other

Osmosis

-the diffusion of water across a membrane

-the water will tend to move across the membrane until equilibrium is reached

-once equilibrium is reached, the concentration of water and sugar will be the same on both sides

-the two solutions will then become isotonic

Aquaphorins

-integral membrane proteins that serve as channels in the transfer of water

The concentration is hypertonic when…

The concentration is hypotonic when….

1. The concentration is higher on the outside of the cyosol

2. The concentration is lower on the outside of the cytosol

Isotonic

-the concentrations areequal on the outside and inside of the cell

-the outside of the cell will then be isotonic

Isotonic, Hypertonic, and Hypotonic water movements

Isotonic: water moves in and out

hypertonic: water moves out

Hypotonic: water moves in

The normal condition for plant cells

A hypotonic environment

Turgid cell

Take in water until the cell membrane pushes against the cell wall

Plasmolysis

-occurs in hypertonic environments

-water leaves the plant cell causing the cell membrane to pull away from the cell wall

Flaccid

-occurs in an isotonic environment

-cell membrane is not pushing against the cell wall

Active Transport

-involves ATP

-from low to high concentration

-moves molecules across the cell membrane from an area of low to high concentration

-involves energy (ATP from the mitochondria

Sodium Potassium Pump

-moves 3 Na ions out of the cell for every 2 K ions it moves in

Endocytosis

-cells ingest external materials by folding around them and forming a pouch

-the pouch then pinches off and becomes a vesicle

Phagocytosis

“Cell eating”

-cell engulfs large solid particles

Pinocytosis

“Cell drinking”

-cell brings smaller things in

Exocytosis

-vesicles made by the cell fuse with the cell membrane releasing their contents into the external environments