Download CELL STRUCTURE AND FUNCTION

CHARACTERISTICS OF LIFE
1. composed of cells – either uni/multi
2. reproduce – sexual and/or asexual
3. contain DNA in cells
4. grow and develop
5. use material/energy in metabolic reactions
6. respond to environment
7. maintain an internal balance - homeostasis
8. change over time – evolve as a population
ORGANIZATION OF LIFE




Cells are the basic unit of life.
Groups of cells that perform a similar function are
tissue.
At least two tissues combine to form an organ.
Organs that carry out similar functions are organized
into systems.
CELL THEORY TIMELINE
Before the 17th century, no one knew cells existed.
Most cells are too small to be seen with the unaided eye.
1600’s – Microscopes were invented.
Robert Hooke, an English scientist, made an improved
microscope and viewed thin slices of cork viewing plant cell
walls. Hooke named what he saw “cells”.
Anton Von Leeuwenhoek, a Dutchman, developed lenses with
a stronger magnification to view microscopic organisms.
1800’s – Cell theory was formed.
Matthias Schleiden (German botanist) & Theodore Schwann
(German zoologist) stated that all plants and animals were
made of cells.
Rudolf Virchow (German physician) stated that cells only arise from pre-existing cells.
Virchow’s idea contradicted the idea of spontaneous generation (idea that nonliving things
could give rise to organisms).
Principles of the Cell Theory
1. All living things are made of one or more cells.
2. Cells are the basic unit of structure & function in organisms.
3. Cells come only from the reproduction of existing cells.
TYPES OF CELLS






PROKARYOTES
Lack nucleus
Lack organelles
Only unicellular
EUKARYOTES
Have nucleus
Have membrane
bound organelles
Uni-/Multicellular
Only Example bacteria
Examples animal, plant,
fungi, protist
Cells differ in size, shape and function.
ALL cells have these components –
BOTH prokaryotic and eukaryotic cells:
Endosymbiosis theory: All organelles seem to share many properties with bacteria. Lynn Margulis proposed
endosymbiosis hypothesis: that organelles derived from ancient colonization of large bacteria (became the
eukaryotic cell) by smaller bacteria (became the mitochondria, chloroplast, etc.) Symbiosis = "living together". In
other words ---- eukaryotic cells evolved when prokaryote cells engulfed or absorbed other cells!
CELL STRUCTURE AND FUNCTION
Organelles are specialized structures INSIDE the cell that have their own functions.
Although the cytoplasm and ribosome are not considered organelles, they are still structures
found in the cell. Organelles function together to help the cell carry out all of life’s
activities.
Remember: ONLY EUKARYOTIC CELLS HAVE ORGANELLES!!!!
STRUCTURE
Cell or Plasma Membrane
FUNCTIONS
 Double membrane barrier consisting of
phospholipids and proteins -- separates
the intracellular fluid within the cell and the
extracellular fluid outside the cell.
 Controls the movement of materials into
and out of cell to maintain homeostasis
Cell Wall
 Thick, inflexible outer layer surrounding
the cell membrane that provides support
and protection
 Found in all cells BUT animal cells
Cytoplasm
 Semi-fluid matrix (cytosol) containing
organelles
 Provides support and protection for
organelles
Chromosomes (Chromatin)
 Contain the DNA found in the nucleus (of
eukaryotic cells) and found in the nucleoid
region (of prokaryotic cells)
 Prokayotes have a one, circular
chromosome. Eukaryotes have linear
chromosomes.
Nucleus
 Contains the genetic material (DNA) that
controls all cellular processes
 Genetic blueprint for cellular proteins –
dictates type and amount of proteins
synthesized
STRUCTURE
Nuclear Membrane
(nuclear envelope)
Nucleolus
Ribosomes
FUNCTIONS
 Double membrane barrier – outer layer is
continuous with rough ER and inner lining
maintains shape of nucleus
 Pores allow substances to pass –
regulates transport of molecules into and
out of the nucleus
 Dense cluster of RNA and proteins that will
be assembled into subunits of ribosomes –
RIBOSOMES are produced!
 Synthesizes proteins – PROTEINS are
produced!
 Free ribosomes synthesize soluble
proteins that function in the cytosol or
other organelles.
Endoplasmic Reticulum (ER)
 Ribosomes on the Rough ER synthesize
proteins to be exported from the cell.
 Membrane system of channels and flatten
sacs that is continuous with the nuclear
membrane and extends through cytoplasm
– transports materials
 Rough ER – has ribosomes on surface;
manufactures secretory proteins that will
be wrapped in transport vesicles for
outside transport
Golgi Apparatus
 Smooth ER – no ribosomes on surface;
contains enzymes for lipid metabolism
 Flattened sacs that contain enzymes for
modification and packaging of proteins and
lipids from the ER
 Packages proteins and lipids inside
transport vesicles and sends them to their
destination
STRUCTURE
Vacuole
FUNCTIONS
 Vesicles that store water, amino acids,
sugars, metabolic and toxic waste
 Plant cells have a large vacuole
Lysosomes
 Vesicle containing digestive enzymes that
digest ingested pathogens (bacteria or
viruses) and nonfunctional organelles
Peroxisomes
 RARELY found in plant cells
 Vesicles containing enzymes (oxidase and
catalase) that detoxify harmful or toxic
substances
Chloroplast
 Site of photosynthesis - transforming
sunlight energy directly into food
 Contains green pigment called chlorophyll
 Has own DNA and can self-replicate
Mitochondria
 NOT found in animal or fungi cells
 Site of aerobic cellular respiration - Uses
energy from food to make ATP (adenosine
triphosphate) that the cell can use to grow,
develop and move
 Has own DNA and can self-replicate
Cytoskeleton
Centrioles
 Very active cells have more mitochondria
 Network of protein filaments - microtubules
and microfilaments
 Help give the cell shape, movement of
organelles inside cell and provide
support/strength
 Microtubules grow out of centrosome
(central area of cell) and form centrioles
 Produce spindle fibers for separating
chromosomes during nuclear division
STRUCTURE
Cilia
FUNCTIONS
 Short, more numerous hair like structures
that assist in cell movement or propelling
foreign substances around the cell
Flagella
 Long whip like tail used for cell movement