Download I1-3 Cell organelle notes

Chapter #7 Eukaryotic Cells
I.
Discovery of the Cell
A. Robert Hooke
1. 1665 – observed cork under a microscope
a. Noticed other plants contained “little boxes”.
b. Named “boxes” cells
B. Cell Theory – took 150 yrs
1. All living things composed of one or more cells
2. Cells – Basic unit of structure and function in organisms
3. Cells reproduce
II.
Cell Diversity
A. Size
1. Few (chicken, frog eggs) lg enough to see with naked eye
2. Most 10-50 micrometer diameter
3. Size limited by ration B/T outer surface area and volume
(increased size, volume increases more rapidly than surface area,
so eventually not enough nutrients can enter cell)
B. Shape
1. Varies by function
a. Nerve cells – long extensions – transmit impulses
b. Skin Cells – flat – cover body surfaces
c. White blood cells (WBC’s) change shape to fit where needed
C. Internal Organization
1. Organelles – perform specific functions like body organs
2. Cell membrane – thin membrane that surrounds cell
3. Nucleus – lg organelle near center contains majority of genetic info
4. Eukaryotes – cells that contain a membrane-bound nucleus
5. Prokaryotes – Unicellular organisms that lack a membrane-bound nucleus
(bacteria)
III.
How do cells obtain nutrients and eliminate waste?
A. Cell membrane – selectively permeable
1. Controls how easily substances pass in and out of the cell.
B. Cell membrane composition
1. Phospholipids (see pg 188 and 189)
a. Polar head – loves water soluble molecules (hydrophilic)
b. Nonpolar tail – repels water soluble molecules (hydrophobic)
**heads – point outward, tails – interior
C.Membrane Proteins
1. Allow cell to transport molecules across membrane
2. Form channels or pores
IV.
V.
VI.
How do cells maintain homeostasis?
A. Prokaryotes – very simple (bacteria)
B. Eukaryotes
1. Cytoplasm – gel-like material that fills cells
2. Cytoskeleton – protein fibers that support structures in the cell
3. Organelles – carry out essential cell processes
C. Organelles (see pg 199 and fill out notes on structure and function)
1. Nucleus
2. Ribosomes
3. Endoplasmic Reticulum
4. Golgi Apparatus
5. Lysosomes
6. Mitochondria
7. Chloroplast
8. Cell wall
9. Cilia and flagella
10. Nuclear membrane
11. Nucleolus
Plant Cells
A. Have many of the same organelles, but also include:
1. Cell wall – (look up definition in text)
2. Vacuoles
a. Can occupy 90% of plant cell’s volume
b. Filled with fluid
c. Store water, enzymes and waste products
3. Plastids
a. Store starch or fats
b. Some contain pigments (absorb light)
4. Chloroplast
a. Most important plastid
b. Contains green pigment called chlorophyll
c. Site of photosynthesis
d. Other plastids can have different colors of pigment
Multi-cellular organization
A. Tissues – groups of cells that carry out a specific function
1. Epithelial tissue – forms surface covering of skin and inside
linings
2. Muscle tissue – cells contract
3. Nervous tissue – cells transmit messages
**many other tissue types
B. Organs – made from tissues to interact and perform specific functions
1. Example – stomach organ
a. Contains muscle tissue to “grind” food
b. Contains epithelial tissue – secretes acid
c. Contains connective tissue – holds stomach parts together
VII.
VIII.
d. Contains nervous tissue – transmits hunger or stomach pain
to brain
C. Organ Systems – made of organs that work together
1. Example – digestive system – mouth, esophagus, stomach,
intestines, and other organs all work together to digest food.
Biology – Study of life
A. 8 characteristics of life (record from pg 7 in text)
How do REAL scientists form opinions?
A. Pseudoscience – areas of study that try to imitate science without support
from the scientific method (ghost hunters, ancient aliens, etc.)
B. Theory – an explanation supported by many observations and experiments
by experts in a particular field.
C. How do scientists form a theory?
1. An initial hypothesis is tested with research, investigation and
experimentation
2. Peer review – the scientist presents the hypothesis and evidence
to other experts
3. Debate – other experts debate and question the new ideas
4. Further testing – other experts try to replicate the results
5. Theory – the hypothesis becomes a theory when MOST scientists
(not all) accept the results and form the same conclusion
6. New information – CAN cause a theory to be rejected or altered
(must go through the same initial steps #1-5)