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The Diversity of Cells Ch. 3-1. How were they discovered? ~ 1665 - Robert Hooke looked at a slice of cork - saw "little boxes" and called them "cells" ~ 1675 - Anton von Leeuwenhoek first to observe pond water under a microscope - PowerPoint PPT Presentation
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How were they discovered? ~ 1665 - Robert Hooke looked at a slice of cork
- saw "little boxes" and called them "cells"
~ 1675 - Anton von Leeuwenhoek first to observe pond water under a microscope
Over next 150 years, people like Schleiden, Schwann, and Virchow researched cellsThis led to…
Cell Theory - 3 parts1.) All living things are composed of 1 or more cells 2.) In organisms, cells are basic units of structure and function3.) Cells are produced only from existing cells
The Diversity of Cells Ch. 3-1
Cells must be small!~ must be able to exchange materials
in and out of the cell
~ move materials within the cell
~ efficiency depends on ratio of surface area to volume
*small cells are more efficient~ Cell shape can affect how it works too...
ex: skin cells are flat and thin, nerve cells are long and skinny - these shapes help it to work better!
Characteristics of all cells:1.) Cell membrane - (plasma membrane)
* separates the cell's insides from the material outside the cell* regulates what moves in and out of the cell*necessary for life
2.) Cytoplasm - everything inside the cell except the cell's genetic make-up (DNA)* cytosol - fluid portion!
3.) Ribosomes - structures on which proteins are made* found in cytosol
2 Types of cells:1.) Prokaryotes - single-celled organisms
~ NO NUCLEUS!!
* 3.5 by old - very small * cannot do many specialized functions* some have flagella or cilia to help move around
a.) Eubacteria - these are common bacteria!* ARE EVERYWHERE!!* can be very helpful - in your gut* can also be harmful - cause disease
b.) Archaebacteria - similar to bacteria but have different ribosomes, different type of cell wall, and live in harsh environments
~ 3 types:*heat-loving - live in hot springs or by thermal vents*salt-loving - live in very salty water*methane-making - live near volcanic vents and in
swamps
Extremophiles!
2.) Eukaryotes * have a true nucleus
* eu: true karyote: kernel
* have organelles that carry out specific functions
Can be unicellular or multicellular!
Each cell has many compartments-* divided by membranes that make little areas for specific structures
Cell membrane - made of phospholipids
hydrophilic heads
hydrophobic tails
hydrophilic heads
Eukaryotic CellsCh. 3 - 2
repels water
sticks to water
~ framework called a cytoskeleton~ made of microfilaments, microtubules, and intermediate
fibers~ all work to give the cell support, shape, help it move, and stay organized
is selectively permeable!!
Nucleus:~ has nuclear envelope with pores (holes)
~ contains DNA
~ has nucleolus that makes ribosome parts
*these parts are put together outside the nucleus
Ribosomes:
~ make proteins to be used in or outside the cell
a put these in a package called a vesicle
The organelles that do this packaging? ER and Golgi apparatus!
Endoplasmic Reticulum (ER):~ moves proteins through the cell
2 kinds:* Rough ER - has ribosomes on it!
~ looks rough!~ makes and packages proteins to go to the GA
*Smooth ER - no ribosomes~ makes lipids and breaks down toxic
substances
Golgi Apparatus (GA):~ modifies, sorts, and packages cell products~ when finished, the package leaves the GA and often leaves the cell
Golgi Apparatus!
Storage and Maintenance:
Lysosomes: ~ vesicle that has enzymes to break down large molecules~ also recycles old, damaged, or unused organelles
Vacuoles:~ large spaces for storage~ plants have large central vacuoles for water storage
Chloroplasts:~ PLANTS ONLY!!~ uses light energy to make sugar
Mitochondria:
~ Powerhouse of the cell - like a battery!~ makes ATP - energy currency, remember?
mitochondrion
Organization of Living Things3-3
We can order cells into different levels of organization:
1.) Tissues - group of cells with similar structures and functions
Ex: muscle tissue
2.) Organs - dif. tissues come together to make an organ that has a specialized structure and function
Ex: heart - made of muscle, nerve and other tissues
3.) Organ systems - organs working together with major body functions
Ex: circulatory system - made of heart, blood vessels, and blood
4.) Organism - anything that can perform life processes by itself
*unicellular - made of just one cell~no specialization
Only eukaryotes have true multicellularity (more than one cell)~ they come from one cell that divides and then those cells differentiate, or
become specialized
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