CHAPTER 4 TEST REVIEW Flashcards
what are membrane organelles? examples
Membrane-bound organelles
* Enclosed by a membrane
* Separates contents from cytosol
* Includes endoplasmic reticulum, Golgi apparatus, lysosomes,
peroxisomes, mitochondria
what are non membrane organelles? examples
Non-membrane-bound organelles
* Not enclosed within a membrane
* Composed of protein
* Includes ribosomes, cytoskeleton, centrosome, proteasomes
what are the general functions of a cell?
Cells perform general functions:
* Maintain integrity and shape of a cell
* Dependent on plasma membrane and internal contents
* Obtain nutrients and form chemical building blocks
* Harvest energy for survival
* Dispose of wastes
* Avoid accumulation that could disrupt cellular activities
* Some are also capable of cell division
* Make more cells of same type
* Help maintain tissue by providing cells for new growth and
replacing dead cells
what are the types of lipids
Phospholipids
* Cholesterol
* Glycolipids
what is the difference between of integral and peripheral proteins
Integral proteins
* Embedded within, and extend across, phospholipid bilayer
* Hydrophobic regions interact with hydrophobic interior
* Hydrophilic regions are exposed to aqueous environments
on either side of membrane
* Many are glycoproteins with attached carbohydrate
groups
Peripheral proteins
* Not embedded in lipid bilayer
* Loosely attached to external or interior surfaces of
membrane
what are the functional categories of proteins
transport proteins
cell surface receptors
identity markers
enzymes
anchoring sites
cell-adhesion proteins
define- tonicity
Tonicity—the ability of a solution to change the volume or
pressure of a cell by osmosis
what are isotonic solutions and what does it mean?
Both cytosol and solution have same relative
concentration of solutes
* For example, normal saline with a concentration of 0.9%
NaCl
* Commonly used in IV solutions
* No net movement of water
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what are hypotonic solutions and what does it mean?
Solution has a lower concentration of solutes, higher
concentration of water than in cytosol
* For example, erythrocytes in pure water
* Water moves down concentration gradient from outside
cell to inside
* Increases volume and pressure of cell
what are hypertonic solutions and what does it mean?
Solution with a higher concentration of solutes than cytosol
* For example, erythrocytes in 3% NaCl water solution
* Water moves down concentration gradient
* Moves from inside cell to outside
* Decreases volume and pressure of cell
* Crenation—cell shrinks
what happens to RBC in the solutions
in isotonic solutions , no change
in hypotonic solutions, water enters and it swells
in hypertonic solutions, water leaves cell and it shirks
what are the three types of endocytosis?
phagocytosis, pinocytosis, receptor-
mediated endocytosis
clinical view 67 Clinical View: Familial Hypercholesteremia
- Inherited genetic disorder
- Defects in LDL receptor or proteins of LDLs
- Interfere with normal receptor-mediated endocytosis of
cholesterol - Results in greatly elevated cholesterol
- Causes atherosclerosis
- Greatly increased risk of heart attack
types of ER
Rough ER
* Protein production by ribosomes, inserted into ER
* Original structure of protein changed
* Transported out in enclosed membrane sacs
* Transport vesicles shuttle proteins from rough ER lumen to Golgi
apparatus
Smooth ER
* Diverse metabolic processes vary by cell
* Functions
* Synthesis, transport, and storage of lipids
* Carbohydrate metabolism
* Detoxification of drugs and poisons
cis face vs trans face
Cis-face
* Proximal to ER
* Trans-face
* Distal from ER
clinical view—93 Clinical View: Lysosomal Storage Diseases
Group of heritable disorders
Accumulation of incompletely digested molecules within
lysosomes
Mutation in genes for lysosomal enzymes
For example, Tay-Sachs disease
* Lack enzyme needed to break down complex membrane lipids
* Lipids accumulate within nerve cells
* Paralysis, blindness, deafness, followed by death by age 4
componets of the cytoskeleton
Microfilaments
Intermediate filaments
Microtubules
structures on the external surface of a cell
Cilia
* Hair-like projections that move substances along cell
surface
Flagella
* Longer and wider than cilia; propels entire cell
Microvilli
* Extensions of plasma membrane that increase surface
area
cilia vs flagellum
Cilia
* Hair-like projections that move substances along cell
surface
Flagella
* Longer and wider than cilia; propels entire cell
membrane junctions
Tight junctions
* Strands or rows of proteins linking cells
* Prevent substances from passing between cells
* Requires materials to move through, rather than between cells
* Maintain polarity of epithelia
Desmosomes
* Composed of proteins that bind neighboring cells
* Hemidesmosomes anchor basal layer of cells of epidermis to
underlying components
Gap junctions
* Form tiny, fluid-filled tunnels
* Provide direct passageway for substances to travel between cells
(For example ions between cells in cardiac muscle)
histones- define
Each double helix is wound around nuclear proteins
chromatin- define
When not dividing, DNA are in form of finely filamented
mass
chromosomes–define
When dividing, DNA chromatin becomes tightly coiled mass
transcription vs translation
Translation
* Synthesis of a new protein
* Occurs at ribosomes within cytoplasm
* mRNA threaded through ribosome
* Code in nucleotide sequence of mRNA translated
* Converted into amino acids to produce protein
Transcription
* Ribonucleic acid
* Copy of a gene formed from
DNA in nucleus
