Download • Outline the Cell Theory. • Discuss possible exceptions to the cell

BILL
• Outline the Cell Theory.
• Discuss possible exceptions to the cell
theory.
BILL # 2 MARKSCHEME
• Cell Theory states that:
• Living organisms are composed of cells
• Cells are the smallest unit of life
• Cells come from Preexisting Cells
• Possible Excpetions
•
•
•
•
Skeletal Muscle Fibers (Large, multi-nucleated)
Fungal Hyphae (not divided up into individual cells)
Unicellular Organisms considered acellular
Some organs contain extracellular material
THE CELL THEORY
MR. VAN ROEKEL
9-9-14
ASSESSMENT STATEMENTS 2.1
• 2.1.1 Outline cell theory:
• 2.1.2 Discuss Evidence for cell theory
• 2.1.3 State that unicellular organisms carry out all the functions of lives
• 2.1.4 Compare the relative sizes of molecules, cell membrane thickness, viruses,
bacteria, organelles, and cells using the appropriate SI unit
• 2.1.5 Calculate the linear magnification of drawings and the actual size of
specimens in images of known magnification.
• 2.1.6 Explain the importance of the surface area: Volume ratios as a factor limiting
cell size.
• 2.1.7 State that multicellular organisms show emergent properties
• 2.1.8 Explain that cells in multicellular organisms differentiate to carry out
specialized functions by expressing some of their genes but not others
• 2.1.9 State that stem cells retain the capacity to divide and have the ability to
differentiate along different pathways
• 2.1.10 Outline one therapeutic uses of stem cells
THE CELL THEORY
• All living things are made of one or more cells
• Cells are the smallest unit of life
• All Cells come from pre-existing cells
All living things are made of
Unicellular organisms are singlecelled and can carry out all of the
functions of life independently.
Multicellular organisms have
specialized cells to carry out specific
functions.
C
E
L
L
S
Longitudinal section of a root tip of Maize (Zea mays)
by Science and Plants for Schools on Flickr (CC) http://flic.kr/p/bNNM6M
EVIDENCE FOR THE CELL THEORY
• All Living Things are made of cells
• Robert Hooke- first observed cork
cells using homemade microscope.
Coined the term “cells”
• Antonie van Leeuwenhoek- first to
observe living cells, described them as
‘animalcules’
Cells are the smallest units of
life.
• Specialized
structures within
cells (organelles)
carry out different
functions.
• Organelles cannot
survive alone.
Paramecium multimicronucleatum
by Proyecto Agua on Flickr (CC) http://flic.kr/p/7W7J3y
EVIDENCE FOR THE CELL THEORY
• Cells are the smallest unit of life
• Many cells carry out the functions of life
(nutrition, growth, reproduction, etc…)
• Unicellular organisms do these on own
• Multicellular organisms have specialized
cells to carry out all functions of life
All cells come from preexisting cells.
• All life evolved from simpler ancestors.
• Cells multiply through division.
• Mitosis results in genetically
identical diploid daughter cells.
• Meiosis generates haploid gametes (sex cells).
4-cell stage of a sea biscuit by Bruno Vellutini on Flickr (CC) http://flic.kr/p/daWnnS
Evidence for Cell Theory
• All Cells come from pre-existing Cells
• Robert Remak discovers cell division and confirms the
existence of the plasma membrane.
Robert Remak: http://en.wikipedia.org/wiki/Robert_Remak
EVIDENCE FOR THE CELL THEORY
• All cells come from preexisting cells
• Louis Pasteur- Disproved theory of spontaneous
generation. Two containers, one open to environment, one
closed. Growth only occurred in container open to
environment.
EXCEPTIONS TO CELL THEORY?
• Unicellular Organisms (Amoeba)- can they be
considered to be made of cells if only have one
cell?
• Fungal Hyphae- extremely large and multinucleated. Have a continuous cytoplasm
(acellular)
• Viruses-Can be considered living if they cannot
perform functions of life on own?
• Hmm...
UNICELLULAR ORGANISMSS
• Capable of Performing all functions of life:
• Movement
• Respiration/Metabolism
• Nutrition
• Response to environment
• Growth and Development
• Homeostasis
• Reproduction
Some units that I use & know
Unit abbr.
Metric equivalent
kilometer
km
1,000m
1 x 103m
meter
m
1m
1m
centimeter
cm
0.01m
1 x 10-2m
mm
0.001m
1 x 10-3m
millimeter
micrometer
nanometer
μm
nm
write this correctly
0.000 001m
0.000 000 001m
1x
10-6m
1x
10-9m
To Convert
μm = micrometers
We usually use this in discussion of cells.
There are 1,000μm in one mm.
÷ 1,000
X 1,000
X 1,000
X 1,000
MICROSCOPIC SIZES.
Plant Cell
Animal Cell
Nucleus
Bacteria
Mitochondria
100 µm
10-100 µm
3-6 µm
1-5 µm
3 µm
Virus
Ribosome
Membrane
Thickness
Molecules
100 nm
20 nm
10 nm
1 nm
2.1.4 Compare the relative sizes of molecules, cell membrane thckness, viruses, bacteria,
organelles, and cells using the appropriate SI unit.
CALCULATIONS IN MICROSCOPY
Magnification
Actual Size
• Measured Length / Scale bar label
• Measured length / magnification
• Used when you are given an image
w/ scale bar and want to know the
magnification of the picture
• Used when given an image and
magnification and want to know
the actual size of the organism in
picture
2.1.5 Calculate the linear magnification of drawings and the actual size of specimens in
images of known magnification
2.1.5 Calculate the linear magnification of drawings and the actual size of specimens in
images of known magnification
2.1.5 Calculate the linear magnification of drawings and the actual size of specimens in
images of known magnification
2.1.5 Calculate the linear magnification of drawings and the actual size of specimens in
images of known magnification
2.1.5 Calculate the linear magnification of drawings and the actual size of specimens in
images of known magnification
BILL – CELL THEORY
• A student views an image of a cell magnified 350 times. The image is
250 mm long. What is the actual length of the sample in the image?
• A sperm cell has a tail that is 50 μm long. A student draws it 75 mm
long. What is the magnification?
• A student views an image of an elodea cell in his professors notes. The
image has a scale bar that represents 10 μm. The student measures
this scale bar to be 30mm long. What is the magnification of the
image?
• A micrograph has a scale bar of 2µm, which measures 40mm on the
image. Measuring the maximum length of the cell in the image, the
ruler reads 180mm. How long is the cell?
BILL ANSWERS
• 30mm/ 10 μm = 30000/10 = 3,000
x magnification
• 40 mm / 2 μm = 40000 μm / 2 μm = 20,000 x
magnification
• 180 mm/20000 = .009 mm X 1000 = 9
μm