Transcript ON Science Chapter 1 Cells Note slides

UNIT 1
Tissues, Organs, and
Systems of Living Things
Chapter 1: Cells and
More Cells
Chapter 2: Plants:
From Cells to Systems
Chapter 3: Animals:
From Cells to Systems
CHAPTER 1
Cells and More Cells
In this chapter you will investigate the:
• similarities and differences between plant and animal cells
• stages of mitosis and its importance for growth and repair
• stages of the cell cycle and how it relates to cancer
• process of cell division in normal and abnormal cells
Copyright © 2010 McGraw-Hill Ryerson Ltd.
1.1 Studying the Structure of Cells
(Page 7)
The development of the microscope in the 1660s increased
our understanding of the human body and led to the
discovery of cells.
Cell – the smallest unit that can perform the
functions of life
Microscopy – the science of using
microscopes to view samples or objects
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Types of Microscopes
(Pages 8-9)
Leeuwenhoek
Bright field/ Dark field
Fluorescence
Transmission
Electron
Phase-contrast
Scanning Electron
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Cell Structure
(Page 10)
• One
of the first structures to be seen clearly through a microscope
was the nucleus.
• The nucleus is the organelle that controls the cell’s activities.
• Organelles are specialized structures within a cell.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
The Cell Theory
(Page 11)
The Cell Theory was proposed by German scientists in the late 1830s.
Theodor Schwann and Matthias Schleiden used their studies of
plants and animals to formulate the first two ideas. In 1855 Rudolph
Virchow added the final one. The theory states that:
1. All living organisms are made of one or more cells.
2. The cell is the basic organizational unit of life.
3. All cells come from pre-existing cells.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Animal and Plant Cell Organelles
Animal Cells
(Pages 12-13)
Plant
Cells
• The cytosol (the fluid material
between the cell membrane and the
nucleus) is filled with many specialized
organelles.
• There are some important differences
between the organelles found in plant
and animal cells.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
All Cells Use Energy
(Page 14)
Cellular Respiration – a process that releases energy from organic
molecules, especially carbohydrates such as glucose, in the presence
of oxygen
Mitochondria – the site in animal and plant cells
where cellular respiration takes place
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Section 1.1 Review
(Page 15)
Concepts to be reviewed:
• types of microscopes and their use
• cell structure
• The Cell Theory
• similarities and differences between plant and animal cells
• cellular respiration
Copyright © 2010 McGraw-Hill Ryerson Ltd.
1.2 Genes: Answers and Questions
(Page 16)
Chromosome – a thread-like structure made mostly of DNA, found in
the nucleus of a cell
DNA (deoxyribonucleic acid) – material found in the cell nucleus
that contains genetic information
Gene – a segment of DNA that controls protein production
Genome Management Information System, Oak Ridge National Laboratory
http://genomics.energy.gov
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Genes Direct Protein Production
Genome Management Information System, Oak Ridge National Laboratory
(Page 17)
http://genomics.energy.gov
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Genes Direct Protein Production
http://genomics.energy.gov
(Page 17)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
The DNA Code
(Pages 17-18)
In 1953 scientists
James Watson and
Francis Crick
created this model
of DNA (the twisted
ladder design is
sometimes called a
“double helix”).
Copyright © 2010 McGraw-Hill Ryerson Ltd.
DNA Screening
(Pages 19-20)
A karyotype is a micrograph of the chromosomes in a person’s cells.
Individual chromosomes from the karyotype can be mapped and then
be examined for any irregularities.
Chromosome/Gene Map
Karyotype
http://www.genome.gov/Pages/Hyperion//DIR/VIP/Glossary/Illustration/k
aryotype.shtml
Copyright © 2010 McGraw-Hill Ryerson Ltd.
DNA Screening:
Testing for Disorders
(Pages 19-20)
DNA Screening is the process of testing individuals to determine
whether they have the gene or genes associated with a certain genetic
disorders
•
•
•
•
•
PKU (phenylketonuria) – mutation in PAH gene
Down Syndrome – trisomy 21
Huntington Disease - mutation in HTT gene
Cystic Fibrosis – mutation in the CFTR gene
Edwards Syndrome – trisomy 18
Copyright © 2010 McGraw-Hill Ryerson Ltd.
DNA Screening:
Testing for Disorders
(Pages 19-20)
By examining karyotypes some genetic disorders can be seen.
Karyotype of a female with
Edwards syndrome
Karyotype of a female with
Down syndrome
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Issues Related to DNA Screening
( Pages 19-20 )
DNA testing can reveal genetic disorders (such as Down Syndrome,
PKU, Huntington Disease) and can help determine how susceptible a
person might be to ailments such as cancers and heart disease.
The controversy
related to genetic
testing revolves
around a variety of
social issues.
(family) - sensitive
Genome Management Information System, Oak Ridge National Laboratory
http://genomics.energy.gov
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Altering Genes / Transgenic Organisms
(Pages 22-23)
Transgenic Organism – an organism whose
genetic information has been altered with the
insertion of genes from another species. These
organisms are considered to be genetically
modified organisms (GMOs).
Possible Uses For GMOs
• Production of non-allergenic human proteins
• Development of pest resistant crops
• Increased growth of crops and livestock
Concerns
• Spread of disease from GMOs
• Negative effects on ecosystems
• Allergic reactions from eating GMOs
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Cloning
(Pages 24-25)
Cloning – the process of
creating identical genetic copies
of an organism
Pros and Cons of
Cloning
• Pro: Copies are made
of “superior” animals.
(increased milk & meat
production)
• Con: Clones may be
less disease resistant
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Mutations
( Pages 26-27 )
Mutation – a change in the DNA of an organism; usual order of base
pairs is altered which changes genes and effects the proteins produced.
Not all mutations are harmful as they can occur in a non-genetic
segments of DNA.
Mutagen – a substance or factor that can cause a mutation in DNA;
DNA is physically damaged Examples: radiation (X-Rays, UV
radiation), mercury, cigarette tar
UV mutated skin cells
sickle-shaped blood cells
albino American alligator
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Section 1.2 Review
( Page 28 )
Concepts to be reviewed:
• genetic material in the nucleus: DNA, chromosomes, and genes
• the structure of DNA
• DNA screening and related issues
• issues related to altering genes
• transgenic organisms
• cloning
• mutations
Copyright © 2010 McGraw-Hill Ryerson Ltd.
1.3 Cells from Cells
(Page 29)
Cell Reproduction – the process by which new cells are formed
Cells can be produced either asexually
(from one parent cell which divides and
forms 2 identical daughter cells) or
sexually (from two parent cells that each
contribute one chromosome from each
of their pairs).
Cell Division
(Pages 29-30)
Most single celled organisms reproduce by splitting in two (binary
fission), producing two new identical cells, called daughter cells.
In multicellular organisms (such as humans), all body cells (cells
produced for growth and repair / replacement) are also produced
through this process of splitting in two (binary fission), producing
two new cells, called daughter cells.
Mitosis / Cytokinesis and Cell Division
(Pages 32-33)
The genetic material in the nucleus of a cell divides through a
process called mitosis, while the cytoplasm divides by a different
process called cytokinesis.
Mitosis – the process by which the duplicated contents of the
cell’s nucleus divide into two equal parts.
Prior to mitosis the DNA in the nucleus must be replicated.
Chromatids are single
strands of DNA; sister
chromatids are two single
strands that together make
a pair or one chromosome.
DNA Replication
(Page 33)
DNA Replication – during DNA replication each chromosome is
duplicated (creating sister chromatids) with the identical
chromatids remaining attached to each other at the centromere
Genome Management Information System, Oak Ridge National Laboratory
Stages of Mitosis
Stages
of
Mitosis
(Pages 34-36)
1. Prophase
2. Metaphase
3. Anaphase
• DNA is
already
duplicated
• Chromatids
condense and
chromosomes
become
visible
•Chromosomes
align across
the centre
equator of the
cell.
•Centromere
splits apart the
chromatids and
chromatids are
pulled to each
side of the cell
by spindle fibres.
•Two
daughter
nuclei are
formed.
4. Telophase
Cytokinesis
(Pages 37-38)
Cytokinesis completes the process of cell division by dividing the rest of
the cell (the cytosol and organelles) and begins before telophase is
complete. In Animal Cells
In plant cells, a cell plate forms
in the middle of the cell,
eventually becoming a cell wall
that divides the cytoplasm in
two. This division occurs from
the interior outward
In animal cells, the middle
of the cell contracts,
pinching the cell membrane,
and the cell is divided. This
division occurs from the
exterior inward.
In Plant Cells
Diffusion
(Pages 30-31)
Diffusion – the movement of
molecules from areas of higher
concentration to areas of lower
concentration
Copyright © 2010 McGraw-Hill Ryerson Ltd.
The Cell Membrane and Diffusion
(Pages 30-31)
Osmosis – the diffusion of water across a selectively permeable
membrane
Selectively Permeable Membrane – a membrane through which
not all materials can pass; some are kept in and some are kept out
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Cell Growth & Limiting Cell Size
(Page 32)
• A major factor limiting cell size is its dependence on diffusion for
raw materials and waste removal.
• The speed of diffusion depends on the difference in concentration
between the inside and outside of the cell (the concentration
gradient).
The ratio of cell membrane surface area (SA) to cell volume (V) is a
factor that limits cell size. AS CELLS INCREASE IN SIZE, THE
SA/V RATIO DECREASES (making less SA available for diffusion)
Section 1.3 Review
(Page 39)
Concepts to be reviewed:
• the process of cell division
• diffusion and osmosis of substances into a cell
• factors limiting cell size
• DNA replication
• the stages of mitosis
• cytokinesis in animal and plant cells
Copyright © 2010 McGraw-Hill Ryerson Ltd.
1.4 The Cell Cycle
(Page 40)
Cells within the human body have finite life spans. The cell
cycle controls the production (through interphase, mitosis, and
cytokinesis) of new cells of a variety of different types.
Interphase – periods of
growth in the life of a cell;
consists of two growth
stages and a stage of DNA
replication
Cell Cycle Checkpoints
(Page 41)
Cell Cycle Checkpoints – a point in the life of a cell when
proteins determine whether cell division should or should not
occur
Cell Death and Suicide
(Page 42)
Cells “die” when they are damaged due to:
• exposure to toxic chemicals or conditions
• physical forces
• the wear and tear of daily use
When cells die their contents leaks out and can cause irritation,
which can lead to swelling and redness in the surrounding cells
Cell “suicide” occurs when the cell experiences a “preprogrammed death” by genes that code for proteins whose
duty is to kill the cell in specific situations such as the fetal
development of separated fingers and toes
• “suicide” genes code for proteins that kill the cells in
specific situations.
• cell contents are packaged for use by other cells
Cancer and the Cell Cycle
Tumour – an abnormal
clump of cells formed
when cells divide
repeatedly and
excessively
Cancer – cells with
abnormal genetic
material that are
dividing uncontrollably
and can spread to other
parts of the body
interfering with normal
cell functioning
(Pages 43-44)
Section 1.4 Review
Concepts to be reviewed:
• the stages of the cell cycle
• the function of cell cycle checkpoints
• cell death and cell suicide
• cancer and how it is related to the cell cycle
(Page 45)