7th Grade Science
http://www.bergoiata.org/fe/felins/10.htm
© Fall 2005, Pflugerville ISD, 7th Grade
http://www.jonathanpmiller.com/intercalation/B-DNA.jpg
It’s Alive!! Or, Is It?
What Do You Think?
What characteristics do all living
things have in common?
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
There are Six Characteristics of
Living Things.
1. Living things have Cells.
2. Living things Sense and Respond to Change.
3. Living things have DNA.
4. Living things Reproduce.
5. Living things use Energy.
6. Living things Grow and Develop.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
1. Living Things Have Cells
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•
•
•
Every living thing is made up of one or more
cells.
Cells are the simplest collection of matter
which has all the properties of life.
Some cells specialize to do specific jobs.
Examples are nerve cells, muscle cells,
etc…
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
The Cell Theory
• The 3 Basic Components of the Cell
Theory :
• 1. All organisms are composed of one or
more cells. (Schleiden & Schwann)(1838-39)
• 2. The cell is the basic unit of life in all living
things. (Schleiden & Schwann)(1838-39)
• 3. All cells are produced by the division of
preexisting cells. (Virchow)(1858)
© Fall 2005, Pflugerville ISD, 7th Grade
Modern Cell Theory
• Modern Cell Theory contains 4 statements, in
addition to the original Cell Theory:
• 1. The cell contains hereditary information(DNA)
which is passed on from cell to cell during cell
division.
• 2. All cells are basically the same in chemical
composition and metabolic activities.
• 3. All basic chemical & physiological functions are
carried out inside the cells.(movement, digestion,
etc)
• 4. Cell activity depends on the activities of subcellular structures within the cell(organelles,
nucleus, plasma membrane)
© Fall 2005, Pflugerville ISD, 7th Grade
It’s Alive!! Or, Is It?
There are 2 main types of cells.
1. Prokaryotic Cells
- have no nucleus
- found in the kingdom of Monera
- Examples are bacteria.
http://library.thinkquest.org/C004535/media/prokaryote.gif
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Pre-AP
It’s Alive!! Or, Is It?
There are 2 main types of cells
(cont…).
2. Eukaryotic cells
- have a true nucleus (that contains DNA)
- found in more complex kingdoms
(animal, plant, etc…)
http://www.ccnmtl.columbia.edu/projects/biology/lecture1/images/F04071s.jpg
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Pre-AP
© Fall 2005, Pflugerville ISD, 7th Grade
It’s Alive!! Or, Is It?
2. Living Things Sense and Respond to
Change.
•
A stimulus is a change that causes the
activity of an organism to change.
• A stimulus can be internal (from inside).
– Examples are fever or vomiting when sick.
• A stimulus can be external (from outside).
– Example is squinting when the lights are
bright.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
2. Living Things Sense and Respond to
Change (cont…).
•
Homeostasis is the maintenance of a stable
internal environment.
- Our bodies are very good at controlling the
chemical reactions that keep us alive. These
reactions can only take place when conditions
are exactly right.
- Even though our outside conditions may
change, homeostasis keeps our internal
conditions the same.
- Example is body temperature.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
3. Living Things Have DNA.
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•
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DNA stands for deoxyribose nucleic acid.
DNA is the molecule that controls the
functions of a cell.
DNA is passed from parent to offspring.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
4. Living Things Reproduce.
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•
•
Most living things reproduce by sexual
reproduction.
Sexual reproduction requires two parents that
produce offspring that share characteristics of
both parents.
Sexual reproduction produces more diverse
more diverse offspring.
Animals
http://www.jpbutler.com/thailand/images/elephant-and-baby.jpg
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
4. Living Things Reproduce (cont…).
•
•
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Some things reproduce by asexual
reproduction.
Asexual reproduction occurs when a single
parent produces offspring that are exactly the
same as the parent.
This leads to more uniform offspring.
Hydra
http://universe-review.ca/I10-26-hydra.jpg
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
5. Living Things Use Energy
•
•
Metabolism is the total of all of the chemical
activities that the organisms performs.
Metabolism includes:
- Making food.
- Breaking down food.
- Building cells.
- Moving materials in and out of cells.
http://www.faculty.ucr.edu/~insects/systems/metabolism/metabolism.gif
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
6. Living Things Grow and Develop.
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•
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You grow as your body gets bigger.
Developing is the process of changing,
maturing, and going through different
stages.
Growing and developing depends on the
environment and the resources available.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
Levels of Organization
largest
smallest
cell
© Fall 2005, Pflugerville ISD, 7th Grade
Made from Atoms and Molecules
Hierarchy of Structural Organization
•
•
•
•
•
•
Chemical
Cellular
Tissue
Organ
Organ System
Organism
Note: be able to define
each!
© Fall 2005, Pflugerville ISD, 7th Grade
Essential Concepts: The Hierarchy of
Structural Organization
• Chemical
– Atoms & bonds
– Carbon, oxygen, hydrogen,
etc.
• Molecules
–
–
–
–
–
–
•
small inorganic
small organic
proteins
carbohydrates
lipids
nucleic acids
Cell Organelles - from
various molecules
© Fall 2005, Pflugerville ISD, 7th Grade
Essential Concepts: The Hierarchy of
Structural Organization
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•
Cellular level –
–
Cells – the basic
structural and functional
units of the organism
–
Cells are specialized for
particular functions,
e.g., muscle cells are
specialized for
contracting
GnRH cells
Tissue level
–
Groups of different cell
types cooperate to
perform specific
functions
skeletal muscle tissue
© Fall 2005, Pflugerville ISD, 7th Grade
Essential Concepts: The Hierarchy of
Structural Organization
• Organ level - two or
more different
tissue types
organized to
perform specific
functions
• System level connected organs
that cooperate in
related function(s)
© Fall 2005, Pflugerville ISD, 7th Grade
Hierarchy of Structural Organization
• Organism level - all of the
organ systems working
together to maintain life
constitute the living
organism
© Fall 2005, Pflugerville ISD, 7th Grade