Transcript Chapter 3

Chapter 3
The Cellular Level of
Organization
3 main parts of cell
fig 3.1
_______________- forms cell’s flexible
outer surface, barrier, regulates flow,
role in communication
 ____________- all cellular contents
between plasma membrane & nucleus

– 2 compartments- cytosol & organelles

___________- large organelle housing
DNA, contains chromosomes that
contain genes
Cell Membrane
fig 3.2
__________________- permit passage
of certain substances but restricts
passage of others.
 Fluid mosaic- ever moving
phospholipids, mosaic of many different
proteins
 Cholesterol also present
 See cell membrane handout


Membrane
_____________ and
their different
functions
Cytoplasm = cytosol & organelles

_______________- fluid portion of cytoplasm
– 55% of total cell volume
– 75-90% water
• Ions, glucose, a.a., f.a., proteins, lipids, ATP, waste; and
sometimes: lipid droplets, glycogen
– Site of chemical rxns
• glycolysis
• protein synthesis

_________- specialized structures for specific
function in cell growth, maintenance & repro
– Each have own enzymes
– # and type vary from cell type to cell type
– Cooperate to maintain homeostasis
Nucleus






____________________ structure called
nuclear envelope encapsulates
Nuclear pores–larger molec selectively pass
Controls cellular structures
Directs cellular activities
Produces ribosomal subunits in __________
________________ - single piece of DNA
– ____________- segments of DNA control cellular
structure and direct cellular activities
Nucleolus
Spherical body inside nucleus
 Cluster of_____, ______, & _________
 _____________ & ___________ of
rRNA and protein into ribosomal
subunits
 Muscle and liver have many cells

Endoplasmic Reticulum

2 types
– ________ ER - synthesizes glycoproteins
& phospholipids  organelles, inserted in
p.m. or secreted during exocytosis
– ________ ER – synthesizes f.a. & steroids
• inactivates or detoxifies drugs & harmful
substances
• remove P from glucose-6-phosphate
• stores and releases Ca 2+ to trigger muscle
contraction
Mitochondria

____________ thru rxns of cellular
respiration
 Each cell: _____ to __________________
 Muscles, liver, kidney have large #
 Inner membrane folds = cristae
– large surface area for celluar respiration rxns to
take place

Can self replicate
 Matrix contains ribosomes
Ribosome

Site of ____________________
 rRNA and protein
 2 subunits made in nucleolus & come
together in cytoplasm
 Can be:
– ______ to ER – synthesize proteins  p.m.
– __________ – syn proteins used in cytosol
– __________________
Golgi bodies

Modifies, sorts, packages & transports
proteins received from rough ER
 Forms __________________ that exocytose
processed proteins to ECF
 Form membrane vesicles that carry new
molecules to ____________________
 Form transport vesicles carrying molecules to
_______________________
– lysosomes
Lysosome
Digests substances that enter cell via
endocytosis and transport final products
into cytosol
 __________ – digestion of worn out
organelles
 __________ – digestion of entire cell
 Carry out extracellular digestion

Centrioles
Pericentriolar material contains tubulins
that build ___________________ in
non-dividing cells
 Form the mitotic spindles during
_______________

Secretory vesicles

Take proteins to the plasma membrane
& _______________ them to the ECF
– Pancreatic cells release insulin

Form at the exit face of the __________
_____________
Cytoskeleton
Serves as __________ that helps to
determine a cell’s shape & to organize
the cellular contents
 _______________________ of:

– organelles within cell
– chromosomes during cell division
– wholes cells
• phagocytes
Cilia and flagella

___________ – “eyelashes,” short,
hairlike projections
– Composed of 20 microtubules in p.m.
– Move like coordinated oars
– Fluid flow along cell’s surface

________ – whip, similar to cilia, longer
– Move entire cell
DNA= DeoxyriboNucleic Acid

_______________ consisting
– One of 4 nitrogenous bases
• Adenine, cytosine, guanine, or thymine
– Deoxyribose
– Phosphate group

Genetic code
 _________________ helix
– Hydrogen bonds between bases (Figure 3.29)
Fig. 03.32
DNA (2)

Purines pair with pyrimidines
– A -- 2 H bonds T
– C --- 3 H bonds G

Sugar and phosphate create the backbone
 ________________ codes for inherited
differences among humans
 Atleast half is “junk” DNA
 Estimate 35,000-45,000 genes in our DNA
Genes


Hereditary units
__________________ at a definite position
on a particular chromosome
– Humans- 23 homologous pairs of chromosomes


Codes for specific RNA
___________= alternate form of a single
gene that controls the same inherited trait
• Example: gene for body hair can have different alleles:
such as coarse hair or fine hair

___________= total genetic information
carried in cell or organism
DNA Replication






fig 3.29
Helix uncoils, strands separate
Each strand of DNA is able to pair with its
______________ base
Chemical bonds form between neighboring
nucleotides (& H bonds form between bases)
Original DNA is now 2 identical strands, one
goes to each of 2 daughter cells
DNA ______________: catalyzes the
addition of the nucleotide to the 3’ end
During _____________ of interphase
DNA  RNA  protein

________________= process in which
gene’s DNA is used to direct synthesis of
specific protein
– _____________- base triplets of DNA are
template for creating COMPLEMENTARY strand
of RNA
– ________________- RNA to protein

______= complementary sequence of 3 RNA
nucleotides, codes for specific amino acid
Genetic code

Set of rules relating the base triplet
sequence of DNA to the
__________________________of RNA
and the amino acids code for in the
polypeptide sequence
Transcription (DNA  RNA)

_____________________ catalyzes
transcription of RNA
– Must be instructed where to start & end along
DNA strand
• Promoter- special nucleotide sequence near beginning of
gene
• Terminator- sequence specifies end of gene
– Only one of 2 DNA strands can be the template
– RNA polymerase attaches at _______________
Fig. 03.28
RNA, 3 types

_________ =mRNA- directs protein synthesis
 _____________= rRNA- joins w/ ribosomal
protein to make ribosomes
 _______= tRNA- binds a.a. to hold it in place
on ribosome while incorporated into protein.
– One end carries amino acid, other end- triplet of
nucleotides = anticodon -complementary to
mRNA codon
mRNA is a modified product

Not all of the gene actually codes for parts of
the protein!
 _________- DO NOT code for part of protein
 __________ - coding region
 After transcription:
– 1st product = pre-mRNA from which intron will be
removed by small nuclear ribonucleoproteins
(snRNPs)
– NOW, the coding mRNA goes out to cytoplasm
Translation (RNA  protein)
Nucleotide sequence of mRNA specifies
the amino acid sequence of a protein
 ___________ in cytoplasm is where
translation occurs
 Translation always starts at start codon
= _________, which codes for the
amino acid methionine

Cell cycle
fig 3.28

Orderly sequence, _________ cell duplicates
its contents and divides into 2 cells
 Humans - 23 pairs of chromosomes
– _________________- belong to same pair
– One from mother, one from father
– Gene pair at identical sites on the 2 homologs

Chromosomes are duplicated in order to pass
on genes
 Cell cycle has _________________:
interphase & mitotic
Interphase
Phase when __________________
 ______________ additional organelles
and cytosolic components
 State of high ____________________

– Cell does most growing during this phase

G1, S, and G2
– G = gap, S = synthesis
G1 Phase of interphase


Between mitosis and S phase
Metabolically active ________________
organelles & cytosolic components
 Duration of cell cycle varies for different types
of cells
– Embryonic & cancer cells have very short G1

____________- cells that remain in G1 for a
very long time, perhaps never destined to
divide again
– Ex) most nerve cells
S phase of interphase
Between G1 and G2
 _____________________

– 2 daughter cells have genetically identical
material

Once entered into S phase cell is
committed to divide
G2 phase of interphase
Between S and mitosis
 _________________ of cell
 Enzymes & proteins made in
_______________ for cell division
 _________________ replication is
complete

– Involved in mitosis- poles to which
chromosomes are drawn towards
Mitotic phase

fig 3.30
Mitotic phase- nuclear division (mitosis) and
cytoplasmic division (cytokinesis)
 ____________ daughter cells are created & are
identical to the somatic parent cell
 2 sets of chromosomes (from S) are sent into 2
separate nuclei
 ________________ of mitosis:
–
–
–
–
Prophase
Metaphase
Anaphase
Telophase
Metaphase

Centromeres of chromatid pairs
____________ at metaphase plate
– Microtubules of mitotic spindle align the
centromeres
Anaphase

_____________________
– Chromatid  2 chromosomes

Individual chromosomes
__________________ towards opposite
poles
– Pulled by mitotic spindles
Telophase

________________ and ___________
reappear
– Chromosomes uncondense & become threadlike,
diffuse chromatin form

____________________ disappear
 Contractile ring forms __________________
around center of cell
– Plasma membrane pulled progressively inward to
form 2 daughter cells = __________________
Meiosis
fig 3.31-32
“lessing condition of”
 Reproductive cell division that occurs in
________________
 Produces ______________

– Chromosome # reduced in 1/2
– Single set of 23 chromosomes (NOT
homologous pairs)
• Homolog- belong to the same pair
Meiosis (2)

__________ (1n) cells = cell has the single
set of not homologous chromosomes.
– Sperm and egg are haploid cells, all other body
(somatic) cells are diploid

Somatic cells are ______________= 2n
 Fertilization then restores the diploid number
of chromosomes from 2 haploid cells (one
egg, one sperm)
Cellular diversity/cell specialization
Human body ≈ 100 trillion cells
 ≈ 200 cell types
 Vary in:

– ______________________
– ______________________
– ______________________
Cell differentiation (2)

Not all cells look or perform the same function
 _____________ - process of specific
regulation of gene expression
 In general, differentiation is the result of
highly programmed pattern of gene activation
and gene repression
 Gene expression is controlled at __________
– Switches to turn on and off transcription
Surface area-to-volume ratio

Greater for small animals than large 
surface of integument for water or solute
exchange is also greater for smaller animals
– Smaller animals dehydrate or hydrate more
quickly
– Larger animals have lesser oxygen requirements
– Heat gain and loss differs
– Gas exchange
– Absorption of nutrients
– Filtration