Transcript Cell Function - biologyonline.us

Human Biology
CELL
FUNCTION
Instructor
Terry Wiseth
CELL DIVISION
the process of cell division
is essential to the growth
and development of all
organisms
growth and tissue repair
are common occurrences
abnormal cell division is
commonly called cancer
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DNA
REPLICATION
parent cells must
provide
daughter cells with
hereditary instructions
and enough cytoplasmic
machinery to start up with
their own operation
DNA
REPLICATION
Cells divide DNA by:
1) Mitosis
Occurs in somatic cells
Most of the cells of the
body
2) Meiosis
Occurs in germ cells
Sperm and egg cells
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CHROMOSOMES
Chromosomes are
the genetic material
found inside the
nucleus of the cell
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CHROMOSOMES
Consist of condensed DNA and proteins
DNA controls protein synthesis
Controls the appearance of
characters and metabolic activities of
an organism
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CHROMOSOME
DNA loops
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CHROMOSOMES
Each species has a
fixed number of
chromosomes in the
nucleus of each of its
cells
Chromosomes always
exist in pairs in the body
cells
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SOMATIC CELLS
somatic cells in each species of organism
will have the same number of
chromosomes specific to that species
ex: humans = 46
gorillas = 48
pea plant = 14
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CELL CYCLE
Mitosis
M
Gap phase 1
G1
Synthesis phase
S
Gap phase 2
G2
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CELL CYCLE
M
(mitosis)
nuclear division
cytoplasmic division
 G1
(gap 1)
interval before the onset of DNA replication
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CELL CYCLE
S
(synthesis)
replication of DNA
 G2
(gap 2)
interval between completion of DNA
replication and the onset of mitosis
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INTERPHASE
usually the longest phase of the cell cycle
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INTERPHASE
consists of the G1,S, and G2 phases of the cell
cycle
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INTERPHASE
1) the cell increases in mass
2) chromosomes cannot be seen
3) chromosomes are duplicated
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INTERPHASE
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STAGES OF
MITOSIS
Prophase
Interphase 19 hrs
Mitosis 1 hr
Metaphase
Anaphase
Telophase
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PROPHASE
1) chromosomes start condensing
chromatids twist and fold on one another
2) spindle fibers begin to form
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PROPHASE
3) centrioles are duplicated and begin to
migrate to opposite poles
centrioles later give rise to cilia and flagella
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PROPHASE
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PROPHASE
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METAPHASE
1) nuclear membrane disappears
2) spindle fibers attach to chromosome
centromeres
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METAPHASE
3) spindle fibers from opposite poles “pull”
on the chromosomes orientating them at the
equator
4) chromosomes become aligned at the cell
equator
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METAPHASE
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METAPHASE
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ANAPHASE
1) the two sister
chromatids of each
chromosome are
separated
2) chromatids move
to opposite poles
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ANAPHASE
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TELOPHASE
1) the daughter chromosomes arrive at
opposite poles
2) chromosomes begin to unwind and
decondense to a threadlike DNA molecule
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TELOPHASE
3) nuclear membranes form, enclosing
the DNA
4) each new daughter cell has the same
number of chromosomes as the parent
cell
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TELOPHASE
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INTERPHASE
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DIVISION OF THE
CYTOPLASM
the cytoplasm divides during Telophase
cytokinesis- cytoplasmic division
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DIVISION OF THE
CYTOPLASM
animal cells “pinch in two” by a process called
cleavage
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DIVISION OF THE
CYTOPLASM
Abnormal cell division at this point can lead to
physical deformities
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METABOLISM
Metabolism - the capacity to acquire energy
and use it to build, store, break apart and
eliminate substances in controlled ways
Energy - the capacity to
make things happen
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METABOLISM
cells secure, use and lose energy
cells cannot create energy
cells must get energy from somewhere else
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METABOLISM
Most energy available for energy conversion is
stored in covalent bonds
glucose, starch, glycogen and fatty acids
are rich in covalent bonds
When molecules are
broken apart there is
a controlled release
of energy which is
available to make
things happen
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METABOLISM
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CHEMICAL
REACTIONS
Many reactions in the cell result in the
production of ATP or the use of ATP
ex: Cellular respiration
C6H12O6 + O2
CO2 + H2O
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REACTANTS
&
PRODUCTS
reactants
products
products
or
reactants
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METABOLIC
PATHWAYS
Orderly sequence of reactions with specific
enzymes acting at each step
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REACTION
SEQUENCES
If the sequence is interrupted the pathway
does not continue and by-products begin to
accumulate
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BIOSYNTHETIC
PATHWAY
Biosynthetic (anabolism) - small
molecules are assembled into large
molecules of higher energy content
Requires the input or use of ATP
ex:
amino acids
proteins

fatty acids
lipids

glucose
starch
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BIODEGRADATIVE
PATHWAY
Biodegradative (catabolism) - large molecules
are broken down to smaller molecules of lower
energy content
ex: starch
glucose
 protein
amino acids
 lipids
fatty acids
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ENZYMES
PROPERTIES
Able to speed up reactions (million fold)
described as catalytic molecules
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EFFECTS OF TEMPERATURE ON
ENZYME ACTIVITY
Enzymes function best within a certain
temperature range
Enzymes lose their 3-dimensional shape
when exposed to high heat
ex: human cell death - 112 degrees F
ex: Siamese cat – coloring pattern
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EFFECTS OF TEMPERATURE ON
ENZYME ACTIVITY
Siamese cat-- ears and paws are the darkest
part of the body
Heat sensitive enzyme is less active in
warmer regions of the body
Enzyme influences higher melanin
production
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EFFECTS OF pH ON
ENZYME ACTIVITY
Enzymes function best within a certain pH range
most function best at pH=7 (neutral)
exception: pepsin (a stomach cell enzyme)
works best at low pH
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ATP is the energy currency
ATP
of the cell
The breakdown of organic
molecules by the cell
releases energy which is
converted to units of ATP
energy
ATP energy is then utilized
by the cell to perform a
multitude of cell functions
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PATHWAYS LEADING TO ATP
FORMATION
1) Aerobic respiration
2) Anaerobic respiration
O2
Glucose
CO2 + H2O + ATP
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PATHWAYS LEADING TO ATP
FORMATION
1) Aerobic respiration
2) Anaerobic respiration
Glucose
Pyruvate + ATP
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PATHWAYS LEADING TO ATP
FORMATION
1) Aerobic respiration
2) Anaerobic respiration
O2
Glucose
CO2 + H2O + ATP
Pyruvate + ATP
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PATHWAYS LEADING TO ATP
FORMATION
1) Aerobic respiration
requires oxygen
most cells are able to
perform
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PATHWAYS LEADING TO ATP
FORMATION
2) Anaerobic respiration
does not require oxygen
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PATHWAYS LEADING TO ATP
FORMATION
The amount of ATP energy produced by
respiration varies
Aerobic respiration
yields 36 ATP from
1 glucose
Anaerobic respiration
yields only 2 ATP
from 1 glucose
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AEROBIC
RESPIRATION
C6H12O6 + 6O2
6CO2 + 6H2O + ATP energy
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ALTERNATIVE ENERGY SOURCES
IN THE HUMAN BODY
1) Carbohydrates
2) Fats
3) Proteins
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ENERGY SOURCES
very little energy is stored as glucose by the
body
Fats-------------------- 78%
Proteins-------------- 21%
Carbohydrates---- 1%
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END
CELL
FUNCTIONS
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