cell structure study guide Flashcards
The Cell
Basic Unit of Life
Cell Sizes
Prokaryotic Bacteria 1.0-10um
Eukaryotic 10-100um
Eukaryotic
Cells Characteristics of higher forms of life
Prokaryotic
Primary or first type of cell without internal organelles and membranes
Nucleus
Usually the largest organelle in the cell
Enclosed by a nuclear envelope - nuclear membrane
Two layer membrane - lipid bi-layer
Contains chromosomal materials in a complex chromatin mass
Site of DNA reproduction and genetic control of the cell
Chromatin
Complexes of DNA, histones, and associated proteins which make up the chromosomal complex
Chromosomes
Long threadlike associations of genes, composed of chromatin and found in the nucleus of eukaryotic cells
Nucleoulus
A roughly spherical region in the nucleus of non dividing cells, which
consists of nuclear organizers and ribosomes in various stages of production. Ribosomal (rRNA) pass through the numerous nuclear pores to the cytoplasm, where assembly is completed.
Messenger RNA
Transcribed from DNA in nucleus - attaches to Ribosome where genetic information is translated into primary protein structure
Ribosome
Site of Protein synthesis
Are composed of complexes of RNA and proteins
Are found free in the cystol and attached to the endoplasmic reticulum
Cells which have secretory functions have a large number of ribosome - example pancreas secretions of insulin in the human body- enzymatic systems
Endo-Membrane System
Membranes are related directly through physical contact or membranes are related through vesicles of material transport - vesicles are membrane enclosed sacs - cellular vehicles for chemical transports Endo membrane system components: Nuclear envelope Endoplasmic reticulum Golgi apparatus Lysosomes
Endoplasmic Reticulum
Most extensive portion of the membrane systems
Continuous with the outer membrane of the nuclear envelope
Contains two distinct regions – smooth and rough portions
Smooth ER
Lacks ribosomes
Participates in the formation of lipids, phospholipids and steroids
Cells which secrete hormones or related compounds are rich in smooth ER membranes- ex ovaries, testis, skin oil glands
Smooth ER in the liver contains an enzyme that removes phosphate from glucose phosphate and allows glycogen conversion to glucose
Detoxifies drugs and poisons - example liver cells have enzymes that catalyze the addition of hydroxide groups to drug and poisons. This allows them to be excreted from the body drugs
In muscle cells, the ER membrane pumps Ca from the cystosol into the cisternal space.
Stores Ca ions needed in muscle contractions - activated when nerve impulses trigger contraction
Smooth ER
Lacks Ribosomes
Participates in the formation of lipids, phospholipids and steroids
Cells which secrete hormones or related compounds are rich in smooth ER membranes- ex ovaries, testis, skin oil glands
Smooth ER in the liver contains an enzyme that removes phosphate from glucose phosphate and allows glycogen conversion to glucose
Detoxifies drugs and poisons - example liver cells have enzymes that catalyze the addition of hydroxide groups to drug and poisons. This allows them to be excreted from the body drugs
In muscle cells, the ER membrane pumps Ca from the cystosol into the cisternal space.
Smooth ER
Stores Ca ions needed in muscle contractions - activated when nerve impulses trigger contraction
Appears rough because it is covered with ribosomes
It is also continuous with the outer envelope of the nuclear membrane
Manufactures secretory proteins and membranes
proteins destined for secretions
primary site of cell protein formation
