Transcript Cell Structure - Brooklyn High School

Cell Structure
Microscopes
Light
• Uses a beam of light
• Can magnify up to
2000x
• Can observe living
specimens
Electron
• Uses a beam of electrons
• Can magnify up to
500,000x
• Can only observe dead
specimens
• TEM – looks through a thin
layer of tissue
• SEM – Used to observe
external features
Cell Theory
• All living things are made of one or more
cells
• Cells are the basic unit of structure and
function in living organisms
• All cells arise from existing cells
* Memorize this *
Formation of the Cell Theory
• Van Leeuenhoek – created the microscope
and used it to see “animalcules” in pond
water
• Hooke – looked at bark and saw empty boxes
he named “cells”
• Schleiden – looked at plants and determined
they were all made of cells
• Schwann – looked at animals and determined
they were all made of cells
• Remak, Virchow, Redi – biogenesis – “life
comes from life”
Pasture – finally “proved” the theory of biogenesis
Features of all cells
• Cell Membrane – made of phospholipids
– Polar head and non polar tail
– Selectively permeable – only some things pass
through
– Fluid –Mosaic model
•Cytoplasm – fluid
inside the cell
–Organelles “float”
in it
•Ribosomes – make
proteins
•DNA – provides the
instructions for the cell
Prokaryotic Cells
• Do not have membrane bound structures
inside of them
• Cell wall – a rigid outer structure that helps
give shape and provide protection.
• The DNA is a single loop – NOT in a
nucleus!
• Flagella – a hair-like projection used for
movement
• Smaller than eukaryotic cells
Many Bacteria Live in Extreme
Environments
•
•
•
•
Halophiles
Thermophiles
Aerobic
Anaerobic
– Facultative anaerobes
– Obligate Anaerobes
Eukaryotic Cells (Plant and Animal Cells)
• Cells have a nucleus
– Nucleus is where the DNA is located
– Surrounded by a nuclear envelope
• Membrane-bound organelles
– Organelles are structures that carry out specific
jobs in the cell
• May use cilia or flagella for movement or to
move substances across the cell surface
– Cilia are little hairs
• Cytoskeleton – supports the shape of the cell,
helps transport organelles and substances
– Microtubules
• Thin, hollow
• Made of proteins
– Microfilaments
• Smaller than microtubules
• Solid
• Centrioles – help move chromosomes during
cell division
– Made of microtubules
– Found in animals
Endoplasmic reticulum – (ER)
• Rough (RER) – has
ribosomes on it –
makes proteins
• Smooth (SER) – makes
lipids and breaks
down toxins
• Vesicle – a small sac
that is used to
transport substances
• Golgi apparatus –
modifies, packages
and distributes
proteins
• Lysosomes – small sacs that
contain digestive enzymes
• Mitochondria – the cell’s power
plant
– Endosymbiotic theory – A
prokaryote began to live in a larger
cell as the result of a symbiotic
relationship.
• Has a double membrane
• Has DNA – circular like prokaryotes
• Reproduces independently of the cell
Plant Cells
• Cell wall – made of cellulose
• Chloroplasts – site of photosynthesis
– Also thought to be endosymbionts
– DNA is very similar a photosynthetic bacteria
• Central Vacuole – takes up most of the
plant cell – contains water, food, and wastes
– When the vacuole is full, the plant stands
upright
– When it is not full the plant wilts and droops