bio

Cell

the simplest collection of matter that is considered life Form (structure) fits function

Prokaryotic cells

domains Bacteria and Archaea

eukaryotic cells

Protists, fungi, animals, and plants

plasma membrane

All cells Are surrounded by a selectively permeable barrier

cytosol

Contain semifluid substance within the membrane

Chromosomes

carry genes in the form of DNA

Ribosomes

tiny complexes that make proteins (translation from mRNA) based on instructions contained in genes

Eukaryotic cell

most DNA is in an organelle bounded by a double membrane generally much larger variety of membrane-bound organelles

Prokaryotic

DNA is concentrated at the nucleoid, without a membrane separating it from the rest of the cell.

Biological membrane

double layer of phospholipids or a phospholipid bilayer.

Plant and animal cells

A nucleus, endoplasmic reticulum, golgi apparatus, and mitochondria.

Chloroplasts

are only present in plants and other photosynthetic eukaryotes

Nucleus

contains most of the genes in a eukaryotic cell.
Additional genes are located in mitochondria and chloroplasts

Nuclear envelope

Double membrane that separates the nucleus from the cytoplasm

Nucleolus

region in the nucleus where ribosomal RNA (rRNA) is synthesized and assembled with proteins from the cytoplasm to form the large and small ribosomal subunits. The subunits pass through the nuclear pores to the cytoplasm, where they combine to form ribosomes.

Ribosomes

carry out protein synthesis Cell types that synthesize many proteins (pancreas cells) have numerous ribosomes and prominent nucleoli.

Free ribosomes

suspended in the cytosol and synthesize proteins that function within the cytosol

Bound ribosomes

attached to the outside of the endoplasmic reticulum or nuclear envelope

synthesis of proteins

transport into membranes and organelles or out of the cell

metabolism

movement of lipids
detoxification.

Endomembrane system

the nuclear envelope ,endoplasmic reticulum
golgi apparatus , lysosomes ,plasma membrane

Endoplasmic Reticulum

Makes membranes Accounts for more than half the membranes in a eukaryotic cell. Includes network of membranous tubules and sacs called cisternae that separate the internal compartment of the ER from the cytosol

Smooth ER

looks smooth because it lacks ribosomes

Rough ER

looks rough because ribosomes are attached to the outside, including the outside of the nuclear envelope

Functions of Smooth ER

Synthesizes lipids, Metabolizes carbohydrates,
Detoxifies drugs and poisons

Functions of Rough ER

Bound ribosomes, Distributes transport vesicles, secretory proteins surrounded by membranes,
Is a membrane factory for the cell

Transport vesicles

carry proteins from one part of the cell to another.

Functions of the Golgi apparatus

Modifies products of the ER ,Manufactures certain macromolecules, Sorts and packages materials into transport vesicles

Lysosomes

carry out intracellular digestion in a variety of circumstances

phagocytosis

fuses with a lysosome, whose enzymes digest the food.

Mitochondria and chloroplasts

the organelles that convert energy to forms that cells can use for work.

Mitochondria

are the sites of cellular respiration, using oxygen to generate ATP by extracting energy from sugars, fats, and other fuels

Chloroplasts

found in plants and algae, are the sites of photosynthesis

Cytoskeleton

network of fibers extending through the cytoplasm that provides mechanical support and maintains the cell's shape

microtubules

are the thickest of the three types of fiber

intermediate filaments

are fibers with diameters in a middle range

microfilaments

actin filaments are the thinnest

plasma membrane

the living cell from its surroundings and controls traffic into and out of the cell

Selectively permeable

allows some substances to cross more easily than others

Fluid mosaic model

where proteins and phospholipids move freely

Fluidity of Membrane

Membrane molecules are held in place by relatively weak hydrophobic interactions (weaker than covalent bonds), Most lipids and some proteins drift laterally in the plane of the membrane, Rarely flip-flop from one phospholipid layer to the other.

Two major types of membrane proteins

integral and peripheral

Integral proteins

penetrate the hydrophobic interior of the lipid bilayer
If they completely span the membrane they are called transmembrane proteins

Peripheral proteins

not embedded in the lipid bilayer. Loosely bound to the surface of the membrane

Six major functions of membrane proteins

Intercellular joining
Enzymatic activity
Transport
Cell-cell recognition
Attachment to the cytoskeleton and extracellular matrix (ECM)
Signal transduction

Diffusion

the movement of molecules of any substance to spread out in the available space from where they are more concentrated to where they are less concentrated

passive transport

The diffusion of a substance across a biological membrane it requires no energy from the cell to make it happen

Facilitated Diffusion

The passive movement of molecules down their concentration gradient with the help of transport proteins

Two types of transport proteins facilitate the movement of molecules or ions across membranes

channel proteins and carrier proteins.

Channel proteins

provide hydrophilic corridors for the passage of specific molecules or ions.

Aquaporins

water channel proteins facilitate the diffusion of water

Transport ions

ion channels function as gated channels

Carrier Proteins

Some proteins do not provide channels but appear to actually move the solute-binding site and the solute across the membrane as the transport protein changes shape.

Osmosis

the diffusion of water across a selectively permeable membrane Water diffuses across the membrane from the region of lower solute concentration to the region of higher solute concentration until the solute concentrations on both sides of the membrane are equal.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water

Isotonic

solution contains an equal concentration of solutes as the solution on the other side of the membrane

Hypotonic

solution contains a lesser concentration of solutes the solution on the other side of the membrane

Hypertonic

solution contains a greater concentration of solutes than the solution on the other side of the membrane

Active Transport

the movement of solutes across membranes against their concentration gradient