Transcript Cell Structure and Function

Cell Structure and Function
• What is the smallest unit of matter that can carry
on all of the processes of life?
– Cell
• What is an organism with only one cell?
– Unicellular
• What is an organism with more than one cell?
– Multicellular
• All living things are made up of cells
• What led to the discovery of cells?
– Microscopes
Discovery of the Cell
• 1665 Robert Hooke discovered dead plant
cells in a slice of cork using a very simple
microscope
• Anton van Leeuwenhoek discovered living
organisms in 1673
• Matthias Schleiden discovered living plant
cells
• Theodor Schwann found animal cells
Cell Theory
• What is the cell theory?
– The observations that Hooke and
Leeuwenhoek made 150 years earlier led to
the theory that follows
1. All living things are composed of one or
more cells
2. Cells are the basic units of structure and
function in living things
3. Cells come only from the existing cells
The Cell
• What characteristics do all cells share?
– Cell membranes and contain DNA
• What is the difference between prokaryotes and
eukaryotes?
– Pros lack a nucleus and euks contain a nucleus
• What is a nucleus?
– Organelle that directs most of the activities of the cell
and contains the cell’s DNA
Prokaryotes
• Have genetic material that is not contained
in a nucleus
• Generally smaller and simpler than
eukaryotes- not all the time though
• Carry out every activity other living things
do as well
• Examples- bacteria
Eukaryotes
• Generally larger and more complex
• Many are highly specialized, many
structures within cell
• Contain nucleus in which their genetic
material is separated from the rest of cell
• Display great variety, may be displayed as
unicellular organism or multicellular such
as- protists, fungi, animals and plants
Sec 2- Eukaryotic Cell Structure
• Organelles- specialized organs found within the
cell
• Cytoplasm contains the various organelles,
cytosol is the gelatin like fluid, surrounds nucleus
• Nucleus- contains nearly all the cell’s DNA and
with it the coded instructions for making proteins
and other important molecules
Parts of the Nucleus
• Nuclear envelope- membrane that surrounds
nucleus, dotted with pores that allows materials to
move in and out
• Nuclear matrix maintains the shape of the nucleus
• Chromatin are strands of DNA and protein
– Chromosomes- threadlike structures that contain
genetic information that is passed on from generation
to generation
• Nucleolus is a small dense region that controls
protein synthesis and is the site of ribosome
synthesis
Eukaryotic Cell
• Mitochondria is where energy is transferred from
organic compounds to ATP
• Ribosomes is the site of protein synthesis
• Endoplasmic Reticulum or ER serves as an
intracellular highway- where lipid components of
cell membrane are assembled
• 2 Types of ER
– Smooth ER and Rough ER
• Rough ER is covered with ribosomes, where
synthesis of proteins takes place
• Smooth ER is not, collections of enzymes that
perform specialized tasks
Eukaryotic Cell
• Golgi Apparatus, appears as a stack of closely apposed
membranes, is the processes, packages, and secretes
substances. Also prepares proteins for export
• Lysosomes, filled with enzymes, are organelles that
digest viruses, bacteria, and old organelles. Also break
down lipids, carbs, and proteins
• Vacuoles- saclike structures that store materials- water,
salts, proteins, carbs
• Mitochondria- organelles that convert the chemical
energy stored in food into compounds that the cell can
use
• Chloroplasts- organelles that convert sunlike energy into
chemical energy- photosynthesis
Cytoskeleton
• Cytoskeleton is made up of protein strands that give the
cell its shape and support, also aids in movement
– 2 major components include microtubules and microfilaments
• Microtubules are larger and hollow, assist in the movement of
chromosomes during cell division
– Centrioles- help organize cell division
– Cilia are short, in large numbers and assist with movement
– Flagella are long, less numbers and assist with movement
• Microfilaments are smaller and contribute to cell
movement and the contraction of muscle cells
– Made of protein-actin
Sec 3- Cell Boundaries
• Cell membrane- controls what goes in and out of the cell,
provides protection and support
• Made up of lipid bilayer- gives membrane flexible structure
that forms strong barrier
• A selectively permeable membrane allows certain substances
in while not allowing other substances
• Cell walls- lie outside of cell membranes, provides
support and protection for cell
– Found in plants, algae, fungi, and many prokaryotes
– Made from fibers of carbohydrates and proteins
– Cellulose makes up cell walls in plants
Diffusion through Cell
Boundaries
• Diffusion is the movement of molecules
from an area of higher concentration to an
area of lower concentration
– Equilibrium- concentration of solute is same
throughout
• No energy needed
• Osmosis is the diffusion of water through a
selectively permeable membrane
Effects of Osmosis on Cells
• Isotonic- concentration of solutes is same
inside and outside the cell
– Water moving in and out of cell
• Hypertonic- solution has higher solute
concentration than the cell
– Water moving out of cell
• Hypotonic- solution has a lower solute
concentration than the cell
– Water moving into cell
Facilitated Diffusion
• Cell membrane channels help move
molecules across the membrane
• Fast and specific- only happens if there is
higher concentration on one side of
membrane
• Does not require energy
Active Transport
• Transportation of materials against
concentration difference
• Requires energy
• Molecules generally transported by
transport proteins
• Endocytosis and exocytosis- processes
that carry larger molecules and clumps of
materials across
Endocytosis and Exocytosis
• Endocytosis and Exocytosis
• Endo- taking material into the cell by
means of infoldings, or pockets of the cell
membrane
– Phagocytosis- extensions of cytoplasm
surrounds particle and cell engulfs it
– Pinocytosis- tiny pockets form around liquid
• Exo- membrane of vacuole surrounding
the material fuses with the cell membrane,
forcing contents out of cell
Sec 4- The Diversity of Cellular
Life
• Compare multicellular organisms to
unicellular organisms?
• Cell specialization- cells throughout an
organism can develop in different ways to
perform different tasks
• Examples
Levels of Organization
• Levels include; individual cells, tissues,
organs, and organ systems
• Tissue-group of similar cells that perform a
particular function
– Examples
• Organ- group of tissues that perform a
particular function
– Examples
• Organ system- group of organs that work
together to perform a specific function
– Examples