Biology of the Cell

Nuclear envelope

Is the double lipid bilayer membrane which surrounds the genetic material and nucleolus in eukaryotic cells.

Endoplasmic reticulum(ER)

System of channels that move materials around the cell (Conveyor belt)

Centrioles

There to help the cell when it comes time to divide

Prokaryotic cell

nucleus absent number of chromosomes one but true chromosome: plasmids cell types usually unicellular (one cell) (some) true membrane bound nucleus absent example bacteria and archaea genetic recombination partial unidirectional transfers of DNA lysosomes and peroxisomes absent microtubules absent or rare endoplasmic reticulum absent mitochondria absent cytoskeleton may be absent dna wrapping on proteins multiple proteins act together to fold and condense prokaryotic DNA folded DNA is then organized into variety of conformations that are supercoiled and wound around tetramers of the HU protein ribosomes smaller vesicles present golgi apparatus absent chloroplasts absent chlorophyll scattered in the cytoplasm Flagella sub microscopic in size composed of only one fiber permeability of nuclear membrane not present plasma membrane with steroid usually no cell wall usually chemically complexed vacuoles present cell size 1-10um

Eukaryota cell

nucleus present number of chromosomes more than one cell types usually multicellular true membrane bound nucleus present example animals and plants genetic recombination meiosis and fusion of gametes lysosomes and peroxisomes present microtubules present endoplasmic reticulum present mitochondria present cytoskeleton present dna wrapping on proteins eukaryotes wrap their DNA around proteins called histones ribosomes larger vesicles present golgi apparatus present chloroplasts present in plants Flagella microscopic in size membrane bound usually arranged as nine doublets surrounding two singlets permeability of nuclear membrane selective plasma membrane yes cell wall only in plant cells and fungi (chemically) vacuoles present cell size 10- 100um

Cilium

A short, microscopic, hairlike vibrating structure.

Peroxisome

Absorb nutrients that the cell has acquired

Microvillus

Are microscopic cellular membrane protrusions that increase the surface area of cells and minimize any increase in volume

Plasmodesma

Are microscopic channels which traverse the cell walls of plant cells and some algal cells, enabling transport and communication between them

Leucoplast

Colorless organelle found in plant cells, used for the storage of starch or oil.

Nucleus

Directs the cell's activities; contains the hereditary material (DNA) (Manager)

Lysosome

Helps maintain and repair cell structures; digests wastes and worn-out parts (Recycling and maintenance center)

Cytoplasm

Jelly-like substance, consisting mostly of water, that is the medium through which materials pass inside the cell (Open space)

Ribosome

Makes proteins according to genetic instructions (Production machine)

Vacuole

Membrane-enclosed sac that stores food, water, and other materials (Warehouse)

Four parts of the nucleus

Nuclear pore Nucleolus Neoplasm Nuclear envelope

plasma membrane

Outer boundary of the cell; regulates the substances that enter and exit the cell (Factory walls)

Golgi apparatus

Package proteins for transport and use outside the cell (Packaging department)

Mitochondrion

Produces energy needed for cellular processes (Power generator)

Cell wall

Right, outer covering of plant cell; made of cellulose and found outside the cell membrane (Outer fence of factory)

Chloroplast

Site of photosynthesis; uses the sun's energy to make food for the plant; contains chlorophyll (Solar-powered generator)