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Cell Structure and Genetic Control
Chapter 3
Cell
•Basic unit of structure and function of the body.
•Highly organized molecular factory.
•Great diversity of function.
•3 principal parts:
•______________________.
•_______________________.
•_____________________.
Eukaryotic cell
Plasma Membrane:
•Material between ___________________ and cell membrane
•Amount in the cell may vary:
•Egg yolk
•Long like in a nerve cell
•Lacking like in _____________________
Plasma Membrane
•Is ________________ permeable.
•Composition:
•Double layer of phospholipids
•Have hydrophobic and hydrophilic areas
•___________________ area is in the center
•_______________________ area is on the outside
•Restrict passage of H20 and H20 soluble ions.
•Composition:
Plasma Membrane
(continued)
•______________________ span or partially span the membrane.
•Give the cell specialized function and selective transport properties
•2 types:
•______________________: partially embedded on one face of membrane
•_____________________: span the width of the membrane
•Composition:
Plasma Membrane
(continued)
•Proteins
•Function:
•______________________
•______________________
•______________________
•______________________
•______________________
Plasma Membrane
(continued)
•Composition:
•Negatively charged _______________ attach to the outer surface.
•Composed of glycoproteins and glycolipids
•Have a negative charge
•Repel one another
•Keeps __________________ from attaching to each other
Plasma Membrane
•_______________:
(continued)
Movement Across…
•cell membrane extends outward, surrounds & engulfs organic matter
•useful in protection against MO
•Removes debris.
•___________________: cell membrane furrows inward
•________________________:
•Nonspecific process.
•Plasma membrane invaginates, fuses, vesicle containing ECM pinches off, and vesicle enters cell.
Movement Across…
•Receptor-mediated ________________:
•Interaction of molecules in ECF with specific membrane receptor
proteins.
•Membrane ___________________, fuses, pinches off and forms
vesicle.
•Vesicle enters cell.
Receptor-mediated endocytosis
Movement Across…
•_____________________:
•Process by which cellular products are secreted into extracellular
environment.
•Proteins and other molecules to be secreted are packaged in vesicles by
__________________________.
•Vesicles fuse with plasma membrane and release contents into extracellular
environment.
Cilia, Flagella, Microvilli
•Cilia:
•Tiny hair-like structures that project from the surface of the cell.
•Stroke in unison.
•_________________________________________________
•Flagella:
•Simple whip-like structure that propels sperm through its environment.
•Microvilli:
•Numerous folds (finger-like projections) increase surface area.
•_________________________.
•Cytoplasm:
Cytoplasm and Cytoskeleton
•___________________________.
•Includes __________________________ and cytosol.
•Highly organized structure with microtubules and microfilaments that function as cytoskeleton.
•Cytoskeleton:
•___________________________________ (microfilaments).
•Spindle apparatus (microtubules).
Lysosomes
•Contain only digestive enzymes.
•“__________________________”
•Autophagy:
•Process that destroys worn-out organelles, so that they can be continuously
replaced.
•______________________ (programmed cell death):
•Lysosomes release digestive enzymes into the cell.
Peroxisomes
•Membrane-enclosed organelles.
•Contain specific enzymes that promote oxidative reactions.
•Oxidize molecules and form H202.
•Promotes removal of H and transports it to oxygen = hydrogen peroxide
•Converts alcohol to acetaldehyde in liver
•Oxidation of toxic molecules by ________________________ is an
important function of liver and kidney cells.
Mitochondria
•Sites for energy production of all cells; but mature _____________________.
•Contain own ______________________, can reproduce themselves.
•Structure:
•Outer membrane: __________________.
•Inner membrane: _____________________
•Cristae and matrix compartmentalize mitochondrion space.
•Have different roles in energy generation.
Ribosomes
•_______________________factories:
•Proteins produced according to genetic information contained in mRNA.
•Located in cytoplasm and on the surface of endoplasmic reticulum.
•rRNA molecules serve as enzymes (ribozymes) required for
protein synthesis.
•Contains 2 subunits composed of rRNA and proteins.
Endoplasmic Reticulum (ER)
•Granular (rough) ER:
•_____________________ on surface, in cells active in protein synthesis.
•Proteins enter cisternae are modified for secretion.
•Agranular (________________) ER:
•Provides site for enzyme reactions in steroid hormone production and inactivation.
•Storage of ________________ in striated muscle cells.
Golgi Complex
•Stacks of hollow, flattened sacks with __________________.
•Modifies proteins, separates according to destination, and packages into vesicles.
•Synthesizes carbohydrates and secretes lipids and glycoproteins
Cell Nucleus
•Heart and brain of the cell
•Contains the genetic material necessary for cell body functions
and reproduction of the species
•_______________________lose nucleus after cell differentiation
Cell Nucleus
•Most cells have ____________________ nucleus.
•Enclosed by inner and outer membrane (________________________).
•Outer membrane is continuous with ER.
•Nuclear pore complexes fuse inner and outer membranes together.
•Selective ____________________________ of proteins and RNA.
•Regulation of gene expression.
•Transport of mRNA out of nucleus to ribosomes.
•Nucleoli:
•DNA contains the genes that code for the production of mRNA.
DNA and Cell Division
•Human DNA contains more organized information than the Encyclopedia
Britannica.
George Sim Johnson
•DNA – Language of Life
•_______________feet of DNA in every cell (100 trillion cells)
•Humans: 23 prs of chromosomes = yield 20,500 proteins
•4 letter code
•Domestic Horse: __________ prs chromosomes
•Wild Horse: _______________prs of chromosomes
•Can they mate and have fertile offspring?
•Human genome project – mapped the 3 billion codes, filled equivalent to
75,490 pages of the New York Times
Gene Expression
•Are present in pairs in the body = homologous chromosomes
•Sex chromosomes:
•XX = ___________________
•XY = ___________________
•ZZ = _______________________
•ZW = _________________________
•Autosomes: all chromosomes other than sex chromosomes
•Gametes = half pairs
Gene Expression
•Genes: regions of the DNA found within the nucleus
•Can be thousands of genes on 1 chromosome
•Each gene contains a code for the production of a particular type
of RNA (mRNA) which makes ____________________
Gene Expression
•Homologous pairs of genes contain a locus = where similar genes
are found
•Ex: BB, Bb, bb are all alleles for color in cattle
•Would all be found in the same locus on DNA from a cow
•Bb are different _________________
RNA Synthesis
•Each gene contains the code for the production of a particular type of
mRNA.
•For the genetic code to be translated into synthesis of a particular protein, the DNA code
is copied onto a strand of RNA (genetic transcription).
•DNA nucleotides:
Nucleotides
•.
•.
•.
•.
•RNA nucleotides:
•.
•.
•.
•.
Types of RNA
•4 types of RNA produced within nucleus by transcription.
•Precursor mRNA (__________-mRNA):
•Altered in nucleus to form mRNA.
•Messenger RNA (____________RNA):
•Contains the code for synthesis of specific proteins.
•Transfer RNA (_________RNA):
•Decodes genetic message contained in mRNA.
•Ribosomal RNA (__________RNA):
•Forms part of the ribosome structure.
Protein Synthesis
•Each mRNA passes through ribosomes forming a polyribosome.
•Association of mRNA with ribosomes is needed for genetic
translation.
•Translation:
•.
Functions of ER and Golgi Complex
•Proteins to be secreted by the cell are synthesized by
_____________ribosome complexes located on granular ER.
•Proteins enter the cisternae, and are modified.
•Leader sequence of amino acids is attracted to membranes of ER.
•Once proteins are in cisternae, the leader sequence is removed.
•Enzymatic removal of regions in protein, alter structure.
Functions of ER and Golgi Complex
Protein Synthesis
(continued)
(continued)
•Each mRNA contains hundreds of __________________
arranged in sequence determined by the complementary base
pairing with DNA.
•Codon:
•Each ________________________ is a code word for a specific amino
acid.
•See figure 3.21
Protein Synthesis
(continued)
Cell Division
•Mitosis: _______________________
•Increase in cell number
•Mature cells (multinucleated) are incapable of mitosis
•Meiosis: _______________________________
•Produces 2 daughter cells as product of 1 cell division
•Prophase:
Cell Cycle: Mitosis (M Phase)
•.
•.
•Metaphase:
•
•
•Anaphase:
•Chromosomes split apart at the centromeres
•Each half goes to its mitotic center
•Telophase:
•Division of cytoplasm, producing 2 daughter cells.
•Cytokinesis: when the cytoplasm divides into 2 equal parts
Meiosis (Reduction Division)
Meiosis (Reduction Division)
(continued)
•Second division:
•Each daughter cell divides, with duplicate chromatids going to each new daughter cell.
•Testes: produce 4 sperm cells.
•Ovaries: produce one mature egg.
Genes in Livestock
•Bos Taurus X Bos bison = Problems with ___________male &
female
•
•
•
•Donkey X Horse
•Mule and Hinny
•Have 63 chromosomes – one of which doesn’t have a homologous twin
When Genes Go Bad
•_____________ of aborted human fetuses have some type of
chromosomal abnormality
•Polyploidy:
•Deletion: when a ___________________is deleted
•Chimerism: possessing 2 or more chromosomes from 2 or more
zygotes
When Genes Go Bad
•Down’s syndrome: extra ____________chromosome or an extra portion of
21
•Klinefelter’s Syndrome: sex chromosomes; XXY, XXXY or XXXXY: are
male, mentally retarded, female characteristics
•___________________: women who have XO sex chromosoms; webbing
of the neck, low-set ears, wide-set eyes; sterility
•_________________________: in pig, most appear to be female with and
XX sex chromosome but have portions of male repro tract