Cell Structure oocytes).
Created by:its_nikkii Organelles and Their Functions
Nucleus:
Introduction to Cells o Location: Often near the center of
the cell.
• Cells are the basic living units of all
o Function: Contains genetic material
organisms.
(DNA) and nucleoli; site of RNA
• Simplest organisms consist of single synthesis and ribosomal subunit
cells, while humans are composed of assembly.
multiple cells. Ribosomes:
• An average-sized cell is one-fifth the o Location: In cytoplasm.
size of the smallest dot you can make o Function: Site of protein synthesis.
on paper with a sharp pencil. Rough Endoplasmic Reticulum (ER):
• Robert Hooke discovered cells in the o Location: In cytoplasm.
late 1600s by observing dead plant o Function: Has many ribosomes
tissue. attached; site of protein synthesis.
• The name "cell" comes from the long Smooth Endoplasmic Reticulum (ER):
rows of monk's rooms (or cells) at o Location: In cytoplasm.
monasteries. o Function: Site of lipid synthesis;
participates in detoxification.
Three Main Parts of the Cell Golgi Apparatus:
1. Plasma Membrane (Cell Membrane) • Location: In cytoplasm.
2. Cytoplasm • Function: Modifies protein structure
3. Nucleus and packages proteins in secretory
Functions of the Cell vesicles.
• Cells are the smallest units that have Secretory Vesicles:
all the characteristics of life. • Location: In cytoplasm.
• Cell Metabolism and Energy Use: • Function: Contains materials
Chemical reactions within cells are produced in the cell; formed by the
collectively called cell metabolism. Golgi apparatus; secreted by
Energy released is used for activities exocytosis.
like synthesis, contraction, and heat Lysosomes:
production. • Location: In cytoplasm.
• Synthesis of Molecules: Cells • Function: Contains enzymes that
synthesize proteins, nucleic acids, digest materials taken into the cell.
and lipids. Different cells produce Mitochondria:
different molecules, determining • Location: In cytoplasm.
their structure and function. • Function: Site of aerobic respiration
• Communication: Cells produce and and ATP synthesis.
receive chemical and electrical Microtubules:
signals to communicate. • Location: In cytoplasm.
• Reproduction and Inheritance: • Function: Supports cytoplasm;
Each cell contains a copy of the assists in cell division and forms
individual's genetic information, components of cilia and flagella.
transmitted to the next generation by
Centrioles:
, • Location: In cytoplasm. • Double semipermeable membrane
• Function: Facilitates the movement barrier.
of chromosomes during cell division. • Allows some, but not all, substances
Cilia: to pass through.
• Location: On the cell surface (many Nuclear Pore:
per cell). • Opening made up of fused nuclear
• Function: Move substances over the membrane.
cell surface. Nucleolus:
Flagella: • One or more small, dark-staining
• Location: On sperm cell surface (one bodies.
per cell). • Site where ribosomes are assembled.
• Function: Propels sperm cells. • Human cells contain 23 pairs of
Microvilli: chromosomes.
• Location: Extensions of the cell Chromatin:
surface. • Tangled, spread-out form of DNA
• Function: Increase surface area of inside the nuclear membrane.
certain cells. • Coils and condenses to form dense,
rod-like chromosomes during cell
division.
Plasma Membrane
Cytoplasm
• Also known as the Cell Membrane.
• Cellular material outside the nucleus
• Outermost component of the cell.
and inside the plasma membrane.
• Fragile, transparent barrier that Cytosol:
contains cell contents and separates
• Gel-like fluid inside the cell.
them from the surrounding
environment. • Also known as intracellular fluid.
• Double layer of phospholipid • Fluid portion of cytoplasm
molecules. surrounding the organelles.
• Extracellular Substances: • Constitutes about 55% of total cell
Substances outside the cell volume.
(e.g., Na+ and Cl− are found in • 75-90% water plus various dissolved
greater concentrations and suspended components.
extracellularly). Organelles:
• Intracellular Substances: • Specialized structures within the cell
Substances inside the cell (e.g., that have characteristic shapes and
glycogen and potassium ions (K+) perform specific functions.
are found at higher concentrations
intracellularly). Organelles (Detailed)
Nucleus Mitochondria:
• The "Headquarters" or "Control • Rod-like, double membrane
Center" of the cell. structures.
• Large organelle housing most of the • The "Powerhouse" of the cell.
cell's deoxyribonucleic acid (DNA). • Inner membrane folds into cristae.
• Site of ribosome formation. • Site of aerobic respiration.
Nuclear Envelope: • Site for ATP synthesis.
Ribosomes: