BIO 1140 Chapter Notes - Chapter 2: Transfer Dna, Nucleoid, Absolute Dating

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Chapter 2.1 Basic Features of Cell Structure and Function
CELLS…
Carry out the essential processes of life
Use chemical molecules or light as energy sources for their activities
Respond to changes in their external environment by altering their internal reactions
Duplicate and pass on their hereditary information as part of cellular reproduction
Multicellular organism: individual consisting of interdependent cells.
Plants
Animals
Prokaryote: organism in which the DNA is suspended in the cell interior without separation
from other cellular components by a discrete membrane.
Cells representing all three domains – Archaea, Bacteria, Eukarya – assume a wide variety of
forms.
Size and shape vary, yet all cells are organised the same
All have structures that perform similar activities
Microscopy: technique for producing visible images of objects that are too small to be seen by
the human eye.
Light microscope: microscope that uses light to illuminate the specimen.
Electron microscope: microscope that uses electrons to illuminate the specimen.
Magnification: the ratio of an object as viewed to its real size.
Resolution: the minimum distance two points in a specimen can be separated and still be seen
as two points.
The shorter the wavelength, the better the resolution
Surface area-to-volume ratio
The volume of a cell determines the amount of chemical activity that can take place
within it
The surface area determines the amount of substances that can be exchanged between
the inside and the outside
Cells increase their ability to exchange materials with their surroundings by flattening,
developing folds, or developing extensions – all to increase their surface area
E.g. intestinal cells have finger-like extensions to increase the surface area of the
intestines
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Plasma membrane: the outer limit of the cytoplasm responsible for the regulation of
substances moving into and out of cells.
Transport protein: a protein embedded in the cell membrane that forms a channel allowing
selected polar molecules and ions to pass across the membrane.
Movement of ions and water-soluble molecules
Maintains the specialized internal ionic and molecular environments required for
cellular life
Water-soluble substances cannot pass through the phospholipid part of the membrane;
so they pass through protein channels instead
Gene: a unit containing the code for a protein molecule or one of its parts, or for functioning
RNA molecules such as tRNA and rRNA.
Genes code for individual proteins
Cytoplasm: all parts of the cell that surround the central nuclear or nucleoid region.
Contains the organelles, cytosol, and cytoskeleton
Many vital cell activities occur here: synthesis and assembly of most molecules required
for growth and reproduction and the conversion of chemical and light energy into forms
that can be used by the cells
Conducts stimulatory signals from the outside to the cell interior
Carries out chemical reactions that respond to these signals
Organelles “little organs”: small, organized structures important for cell function.
Cytosol: aqueous solution in the cytoplasm containing ions and various organic molecules.
Cytoskeleton: the interconnected system of protein fibres and tubes that extends throughout
the cytoplasm of a eukaryotic cell.
Protein-based framework of filamentous structures
Helps maintain proper cell shape
Key role in cell division and chromosome segregation
Nucleoid: the central region of a prokaryotic cell with no boundary membrane separating it
from the cytoplasm, where DNA replication and RNA transcription occur.
DNA-containing central region of the cell
Nucleus: the central region of eukaryotic cells, separated by membranes from the surrounding
cytoplasm, where DNA replication and messenger RNA transcription occur.
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Chapter 3.1 What is life?
The types of elements and atoms found in living things are also found in nonliving forms of
matter.
Living cells obey the same fundamental laws of physics and chemistry as the nonliving
world
Life is defined most effectively by a list of attributes that all forms of life possess:
1. Display order
2. Harness and utilize energy
3. Reproduce
4. Respond to stimuli
5. Exhibit homeostasis
6. Grow and develop
7. Evolve
These properties of life are called emergent because they come about, or emerge, from many
simpler interactions that do not have the properties found at the higher levels
There is a hierarchy of interactions that begins with atoms and progresses through
molecules to macromolecules and cells
There are a small number of biological systems that straddle the line between the biotic and
abiotic worlds.
For example, a virus
The characteristics of life that a virus has are based on its ability to infect cells
They have DNA and RNA but lack the ability to use those nucleic acids to synthesize their
own proteins; cannot reproduce without a host cell
Most scientists do not consider viruses to be alive
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