cell parts

nucleus

-control center of the cell

-contains genetic material (DNA)

-required for building proteins, cell division

-three region: nuclear envelope, nucleolus, chromatin

nuclear envelope

-double membrane with nuclear pores

-encloses the jellylike fluid called the nucleoplasm

nucleolus

-one or more per nucleus

-stains dark

-sites of ribosome assembly

chromatin

-uncondensed DNA wound around histories (proteins)

-present when cell is not dividing

-condenses to form chromosomes during cell division

plasma membrane

-fluid mosaic model

-phospholipid bilayer

-contains cholesterol, proteins, glycolipids

plasma membrane protein roles

-enzymes

-receptors for hormones or other chemical messengers

-transport as channels or carriers

cytoplasm

-material outside nucleus and inside plasma membrane

-include cytosol, inclusions, and organelles

mitochondria

-“powerhouses” of the cell

-carry out reactions in which oxygen is used to break down food into ATP molecules

ribosomes

-made of protein and ribosomal RNA

-sites of protein synthesis in the cell

-found free in cytoplasm or with rough ER

Endoplasmic Reticulum

-fluid filled tunnels that carry substances within the cell

-continuous with the nuclear membrane

-Rough and Smooth

Rough Endoplasmic Reticulum

-studded with ribosomes

-synthesizes proteins

-transport vesicles move proteins within cell

-abundant in cells that make and export proteins

Smooth Endoplasmic Reticulum

-lacks ribosomes

-functions in lipid

-detoxification of drugs and pesticides

-stores calcium in skeletal muscle cells

Golgi Apparatus

-stack of flattened membranes associated with tiny vesicles

-modifies and packages proteins arriving from rough ER via transport vesicles

lysosomes

-membranous “bags” that contain digestive enzymes

-enzymes can digest worn out or non usable cell structures

Peroxisomes

-membranous sacs of oxidase enzymes

-detoxify harmful substances such as alcohol and formaldehyde

-break down free radicals

cytoskeleton

-network of protein structures that extend throughout the cytoplasm

centrioles

-rod shaped bodies made of nine triplets of microtubules

-generate microtubules

-direct the formation of mitotic spindle during cell division

cilia

-move materials across the cell surface

-located in respiratory system to move mucus

flagella propel the cell

-sperm is the only flagellated cell in humans

microvilli

-tiny, fingerlike extensions of the plasma membrane

-increase surface area for absorbtion