Understanding Living Things

1
Understanding Living Things

• Cells, Genetics, and Heredity

Mrs. Strand 6th grade Lockwood Middle School
Harcourt Science Chapter 1
2
Cells, Genetics and Heredity

• Terms
• Cell membrane
• Cell wall
• Cytoplasm
• Mitochondria
• Chloroplast
• Vacuole
• Nucleus
• Chromosome
• Nuclear Membrane

3
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

4
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

5
How Plants Animals Differ

• http//www.beyondbooks.com/lif71/4.asp

6
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

7
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.

8
Microscope Parts

• ____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_______________________

14. ___Coarse Adjustment_______ 13. ____
___fine adjustment_____ 12. Arm
_____________________ 11. ____Base____________
______
9
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

10
How Cells Reproduce

• Terms
• Genes
• Mitosis
• Meiosis

11
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
12
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

13
How Cells Reproduce

• http//faculty.clintoncc.suny.edu/faculty/Michael.
  Gregory/files/Bio20101/Bio2010120Lectures/Bioch
  emistry/biochemi.htm

14
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
15

• Mitosis
• Cell division that produces new body cells

http//www.dartmouth.edu/cbbc/courses/bio4/bio4-1
997/images/mitosis.JPG
http//www.micro.utexas.edu/courses/levin/bio304/g
enetics/celldiv.html
16
Meiosis
The process that forms reproductive cells
http//www.emc.maricopa.edu/faculty/farabee/BIOBK/
BioBookmeiosis.html
http//www.biologie.uni-hamburg.de/b-online/e09/09
b.htm
17
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

18
How Traits are Inherited

• Terms
• Sexual Reproduction
• Dominant
• Recessive
• Punnett Square

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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

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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)

21
Punnett Squares
Used for making predictions


22
Chromosome Theory

• Chromosome theory states that factors, which we
  know are genes, are located on the chromosomes in
  very specific places.