Transcript Cells - Red Hook Central School District

Topic 1
Characteristics of Life
& Cells
Characteristics of Life
1. Cells are the basic unit of life. All living
things are made of one or more cells.
2. Metabolism is the sum of all chemical
reactions in an organism. Since all living
things use energy they undergo
metabolism.
3. Homeostasis is the maintenance of a
relatively stable internal environment.
4. Reproduction is the passing on of
genetic information.
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•
Biotic = living
Abiotic = nonliving
Similarities Among Living Things
• Obtaining nutrients from the environment
• Transportation of materials throughout the
organism
• Breaking nutrients into smaller units to release
chemical energy
• Synthesis – building large units out of small ones
• Growth – increasing the # or size of cells
• Excretion – removal of waste products
• Responding to internal and external stimuli
• Reproduction of the species
Organic Chemistry
• The 4 main elements that all living
organisms are made of include: Carbon,
Hydrogen, Oxygen and Nitrogen
• Organic – describes molecules that
contain both carbon and hydrogen
• Inorganic – Does not contain both Carbon
and Hydrogen
Major Organic Compounds in
the Body
•
•
•
•
Carbohydrates (ex. starches, glucose…)
Lipids (ex. fats, cell membrane…..)
Proteins (muscle, enzymes…..)
Nucleic Acids (the building blocks of
genes)
Major Inorganic Substance in
the Body
•
•
•
•
Water
Oxygen
Carbon Dioxide
Salts (many minerals are classified as
salts)
Levels of Organization in Living
Organisms
• Larger
- Organism
- Organ System
- Organ
- Tissue
- Cell
• Smaller -Organelle
Cell Theory
1. Cells are the basic unit of living things.
All living things are made up of cells.
2. Given #1, all life functions that are
carried out by a living organism are
carried out by a cell.
3. Cells arise from other cells – not nonliving matter.
Exceptions to Cell Theory
1. Viruses are not made up of cells, yet they
can act like living things and do contain
genetic information.
2. The first cell could not have come from
another cell.
Question
• What are 4 differences between a plant
and animal cell?
Differences Between Plant and
Animal Cells
1. Plants have a cell wall, animals do not.
2. Plants have chloroplasts, animals do not.
3. Plants have large vacuoles and animals
have small vacuoles.
4. Animals have many more mitochondria
than plants.
5. Animal cells are more oval shaped and
plant cells are more box shaped.
Organelles
• Cytoplasm – the jellylike substance inside of a
cell that: surrounds organelles, transports
materials in and out of the cell and is the site of
many chem. reactions.
• Nucleus – stores genetic info and controls
metabolism
• Vacuoles – storage sacs for food, water and
waste. (vacuoles in plants tend to be much
larger than those in animals)
• Ribosomes – important to the protein making
process
Organelles
• The Cell Membrane: is selectively
permeable, controls what moves in and
out of the cell and plays a major role in
maintaining homeostasis in the cell
• It is make of a double layered structure
called a lipid bi-layer, proteins and
carbohydrates.
• Mitochondria – contain enzymes used to
extract energy from nutrients
Organelles
• Chloroplasts – only in plants and some
single celled organisms, they contain a
green pigment called chlorophyll which
capture light energy and converts it to
chemical compound used for food
• Cell Wall – provides the cell with structure
and protection. Only in Plants!
Types of Transport in the Cell
Passive Transport: Requires no Energy (ex. sled downhill)
• Diffusion- direct movement determined by concentration
gradient (Areas of high concentration diffuse to areas of
low concentration. (Salt on roads destroying plants ex.)
• Facilitated Diffusion- Transport proteins in the lipid
membrane move molecules along the concentration
gradient faster than normal diffusion (the express lane).
Ex. Glucose
• Osmosis- Diffusion of water
Types of Transport Cont.
Active Transport = Movement against the
concentration gradient, energy is required
in the form of ATP (ex. pulling a sled up
hill) (desert plants use A.T.P. a lot to pull
water up from their roots)
Types of Active Transport
• Endocytosis- moving materials into the
cell
• Exocytosis- moving materials out of the
cell.
• Pinocytosis- cell drinking
• Phagocytosis- cell eating
Digestion in a Cell
• Most proteins and carbohydrates are too
large to enter the cell and must be broken
down first.
• Protein digestion results in smaller
molecules of amino acids
• Carbohydrate (starch) digestion results in
smaller molecules of simple sugars
Signal Recognition
• Receptor Molecule – certain protein molecules
in the cell membrane that can receive chem.
messages (ex. nerve cell communication ex.
Neurotransmitters=N.T.)
• Hormone – chemical produces in the endocrine
glands and responsible for communication b/t
cells
• If nerve cell or hormone communication is
interrupted than homeostasis may be affected.