Understanding Living Things
Cells, Genetics, and Heredity
Harcourt Science
Chapter 1
Mrs. Strand6th grade Lockwood Middle School
Cells, Genetics and Heredity
Terms Cell membrane Cell wall Cytoplasm Mitochondria Chloroplast Vacuole Nucleus Chromosome Nuclear Membrane
How Plants & Animal Cells Differ
The discovery of cells Robert Hooke
One of the first people to see and study the tiny building blocks that made up living things
Gave cells their name, because they looked like small prison cells
Cell Theory
Cells are the basic building blocks of all living things Large organisms have more cells that
can do different things All live activities take place in cells
Heart, lungs, kidneys, skin… New cells are only produced by
existing cells
Nucleus of the cell
DNA Directs the activity of the cell Contains the information and instructions about
how the cell is built and its job Is a chemical Makes up the chromosomes
Nucleus send out instructions in the form of chemicals through tiny openings in the nuclear membrane
How do we see all this cool stuff?
In 1590 Zacharias Janssen was given credit for developing the first compound microscope.
A few years late, Anton van Leeuwenhoek developed a lens that could magnify up to 270 times! Later he was recognized as the first
person to observe microbial life.
Microscope Parts
1. ____eye piece_______2. _______eye tube________________
3. _____objective disc___________4. _____low powered objective____5. _____ med. powered objective___6. _____ high powered objective____
7. ______stage_________________8. _____stage clip______________9. ____slide_______________________10. ____light
source__________________
14. ___Coarse Adjustment_______
13. ____ ___fine adjustment_____
12. Arm _____________________
11. ____Base__________________
Microscope Safety
Carry by the base and the arm Check for shorts
Does the light flicker on and off? When you begin
Clip the slide onto the stage Check from the side to see where your lenses are
Begin with the 4x at its highest position focus
Turn the lens disc to the 10x Focus
Move the lenses up a little bit before advancing to the 40x
How Cells Reproduce
Most living things start out as a single cell. Not all of these cells develop into the same
type of cell. Most living things do not grow at a
constant rate during their life time. The only way for an organism
to grow is for cell reproduction.
http://www.agius.com/hew/resource/sens.htm
How Cells Reproduce
DNA is the blueprint for the entire organism.
DNA codes are used only when they are needed
The nucleus contains the chromosomes. The chromosomes contain the genes
The genes are made of DNA
How Cells Reproduce
http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20101/Bio%20101%20Lectures/Biochemistry/biochemi.htm
How Cells Reproduce
In humans, there are 46 chromosomes in all. (23 from each parent) There are 50,000
genes for each chromosome. Not all of these genes
are activated at all times. This is called differentiation.
http://www.alumni.ca/~laued3e/conclusion.html
Mitosis Cell division that
produces new body cells
http://www.dartmouth.edu/~cbbc/courses/bio4/bio4-1997/images/mitosis.JPG
http://www.micro.utexas.edu/courses/levin/bio304/genetics/celldiv.html
Meiosis
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmeiosis.html
http://www.biologie.uni-hamburg.de/b-online/e09/09b.htm
The process that forms reproductive cells
Variations in Organisms
Most organisms are multicellular and have genes from both parents. Due to the combining of cells that went
through meiosis
Traits that result from combining genes of parents are: hair & eye color, height, left or right handedness
George Mendel
First person to show how traits are passed from parents to offspring
Observed pea plants that he grew in his garden Easy to get Grew rapidly Traits were easy to tell apart Easy to cross different pea plants Little chance for self pollination
Dominant and Recessive Genes
Mendel thought each plant carried two factors for each trait that it showed. Parents make and pass on only one factor to the
offspring. The offspring receives a factor from each parent
and so carries two factors for each trait. Factors may be the same or different Factors may be dominant (stronger) or recessive
(weaker)