Cell Structure and Function

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Cells Smallest living unit Most are microscopic

Discovery of Cells Robert Hooke (mid-1600s) Observed sliver of cork Saw “row of empty boxes” Coined the term cell

Cell theory (1839)Theodor Schwann & Matthias Schleiden “ all living things are made of cells” (50 yrs. later) Rudolf Virchow “all cells come from cells”

Principles of Cell Theory All living things are made of cells Smallest living unit of structure and function of all organisms is the cell All cells arise from preexisting cells (this principle discarded the idea of spontaneous generation)

Cell Size

Characteristics of All Cells A surrounding membrane Protoplasm – cell contents in thick fluid Organelles – structures for cell function Control center with DNA

Cell Types Prokaryotic Eukaryotic

Prokaryotic Cells First cell type on earth Cell type of Bacteria and Archaea

Prokaryotic Cells No membrane bound nucleus Nucleoid = region of DNA concentration Organelles not bound by membranes

Eukaryotic Cells Nucleus bound by membrane Include fungi, protists, plant, and animal cells Possess many organelles Protozoan

Representative Animal Cell

Representative Plant Cell

Organelles Tiny cell structures that are specialized parts of a cell that have specific functions – a cell “organ.”

Cell Functions

Plant Cell

Animal Cell

CELL MEMBRANE – “gate keeper” outer boundary (or layer) of the cell controls the movement of materials into and out of the cell

Cell Parts and Functions Cell Membrane Protects the cell Lets things in and out of the cell Location: around the cell

Common features of all cells 1. Cell Membrane – selectively/differentially permeable (lets some things in and out)

CELL WALL found in plant cells tough rigid boundary – made of cellulose gives cells their shape (it also provides protection, as well as support)

Cell Wall Differences Plants – mostly cellulose Surrounds plasma membrane

CYTOPLASM – “cell fluid” a gel-like material inside the cell Many cellular activities occur here and where the organelles are contained

Cytoplasm Viscous fluid containing organelles components of cytoplasm Interconnected filaments & fibers Fluid = cytosol Organelles (not nucleus) storage substances

Cell Parts and Functions Cytoplasm Gel-like substances, holds all Organelles in cell Location: in cell

NUCLEUS controls cell processes – “brain of the cell” controls cell processes Contains DNA or chromosomes - the heredity material or genetic blueprint of the cell

Nucleus Control center of cell Double membrane Contains Chromosomes Nucleolus

DNA Hereditary material Chromosomes Chromatin DNA Protiens Form for cell division Chromatin

NUCLEAR MEMBRANE – materials pass in and out through tiny holes called porins

Cell Parts and Functions Nuclear Membrane Protects nucleus Lets things in/out of nucleus (pores) Location: around nucleus cell

NUCLEOLUS – ribosomes are made here

Cell Parts and Functions Nucleolus (Nucleoli) Makes ribosomes Location: inside the nucleus (dark spot) cell

Nucleolus Most cells have 2 or more Directs synthesis of RNA Forms ribosomes

CHLOROPLASTS found only in plant cells – “energy processing organelles” found only in plant cells place where food is made for plant cells

Chloroplasts Derived form photosynthetic bacteria Solar energy capturing organelle

Cell Structures and Functions Chloroplast Traps suns energy and Makes food Location: in plant cells

MITOCHONDRIA – “powerhouse” converts food (glucose) to energy (ATP)

Cell Parts and Functions Mitochondria Makes energy/ powerhouse Location: in cytoplasm

Mitochondria Break down fuel molecules (cellular respiration) Glucose Fatty acids Release energy ATP

RIBOSOMES – “protein factories” place where protein is made in the cells some are attached – some float in the cytoplasm

Cell Parts and Functions Ribosome Makes proteins Location: in cytoplasm or Attached to E.R.

ENDOPLASMIC RETICULUM – “conveyer belt” transports synthesized proteins throughout the cell

Cell Parts and Functions Endoplasmic Reticulum (E.R.) Transports materials and sends messages to all parts of the cell Two types: smooth and rough (has ribosomes) Location: attaches from cell membrane to nuclear membrane Rough E.R.

Rough Endoplasmic Reticulum Ribosomes attached to surface Manufacture protiens Not all ribosomes attached to rough ER May modify proteins from ribosomes

Smooth Endoplasmic Reticulum No attached ribosomes Has enzymes that help build molecules Carbohydrates Lipids

GOLGI BODIES sort, modify, process, and ship the proteins through the cell (Also known As GOLGI Apparatus)

Golgi Apparatus Involved in synthesis of plant cell wall Packaging & shipping station of cell

Cell Parts and Functions Golgi Bodies/Apparatus Packages and secretes (gets rid of) waste Location: in cytoplasm

GOLGI APPARATUS

VACUOLES store water, sugar, salts, nutrients, & wastes in cells – “storage” store water, sugar, salts, nutrients, & wastes in cells maintains the proper pressure to provide structure and support in plant cells

Vacuoles Membrane bound storage sacs More common in plants than animals Contents Water Food wastes

Cell Parts and Functions Vacuole Stores food and water Location: in cytoplasm

Vacuole

LYSOSOMES contain chemicals that break down waste materials.

Lysosomes Contain digestive enzymes Functions Aid in cell renewal Break down old cell parts Digests invaders

Cell Parts and Functions Lysosome Contains digestive enzymes Destroys bacteria, old cell parts… Location: in cytoplasm