Ch. 3 - Cellular Level of Organization Flashcards
What makes the plasma membrane a fluid mosaic?
Phospholipids - forming flexible bilayer
Protein - embedded in membrane
Carbs - cell identification on surface
How does cholesterol function in the membrane?
Embedded in both layers, attached to phospholipid tails
- Regulates fluidity (restrains when warm, promotes when cool)
What are 3 types of proteins of cell membrane?
Peripheral (on surface), integral (embedded, amphipathic), transmembrane (subtype of integral, go across)
6 functions of membrane proteins
- Maintain cell shape
- Receptors for signalling molecules
- Enzymatic activity
- Cell recognition
- Intercellular junctions
- Transport
What is the glycocalyx?
Sugary coat on outer surface of membrane, where carbs are found
- functions in cell recognition and cell singaling
What are glycoproteins and glycolipids?
When carbs attach to some proteins and lipids, respectively
Membranes are permeable to what kind of molecules?
Small, nonpolar, uncharged
Membranes are impermeable to what kind of molecules?
Ions, charged, polar
Passive vs. Active Transport
Passive: does not require energy (uses kinetic E), solutes move DOWN conc. gradient, may or may not require membrane prot
Active: requires E, solutes pumped AGAINST conc. gradient, requires membrane prot
Diffusion is the movement of solutes from an area of…
high solute conc to an area of low solute conc
each substance moves down conc gradient independently of other solutes
What is osmosis?
Movement of water from an area of low [solute] to high [solute]
What is an isotonic solution and where does water move?
Equal [solute] to inside of cell
- same amount of H2O will move in and out; no net movement
What is a hypotonic solution and where does water move?
Lower [solute] / higher [water] in solution THAN inside of cell
Water moves inside cell; hemolysis
What is a hypertonic solution and where does water move?
Higher [solute] + lower [water] in solution THAN inside of cell
Water moves out of cell; crenation
Structure and function of cytoskeleton?
Network of fibres
Established/maintains cells shape, provides strength, locomotion, chrom separation during cell division, intracellular transport of organelles
What is the cytoskeleton comprised of? (3)
- Microfilaments (made of actin): controls cell shape + movement
- Intermediate filaments (made of several fibrous proteins): reinforce cell + anchor certain organelles
- Microtubule (hollow tubes made of tubulins): rigidity/shape; anchors organelles; migrates chrom during cell division
What is the structure and function of the centrosome?
Pair of centrioles (composed of 9 triplets of microtubules) + pericentriolar matrix
Microtubule organizing centre; organize spindles for chrom migration during cell division
Compare and contrast cilia and flagella
- both are locomotor appendages + made of microtubules
C - movement is perpendicular, many short cilia
F - drives cell forward, one (long) flagellum
Structure and function of ribosomes?
Particles of rRNA + protein, composed of large + small subunit (made in nucleolus, assembled in cytoplasm)
Carry out prot synthesis
Compare and contrast rough ER and smooth ER
ROUGH - makes membrane + proteins; ribosomes on rough ER make secretory/membrane/organellar prot
SMOOTH - synthesizes lipids, FA, steroids; stores glycogen/calcium; breaks down toxins + drugs
Structure and function of Golgi complex
- stacks of membranous sacs
- receive, modify, sort products from ER, package + send them off
Structure and function of lysosomes
sacs of digestive enzymes budded off Golgi C
- digests cells food + wastes (hydrolyze prot, fat, polysacch, nucleic acids)
- proteins pump H+ into lymen from cytosol to maintain pH of 5
Function of mitochondria
- sites of cell. resp. + triggering apoptosis
How do mitochondria harvest energy?
From food and store this energy as ATP
Function and components of the nucleus?
Genetic control center; directs prot. synthesis
- separated from cytoplasm by nuclear envelope; nuclear pores regulate entry/exit of material; nucleolus where rRNA is synthesized
Describe the steps a protein undergoes from synthesis to secretion
- Nucleus: transcribe gene to mRNA
- Nucleolus: rRNA is synthesized
- Rough ER = ribosomes make protein
- Packages into TRANSPORT V and bring it to Golgi complex
- Golgi packages and sends it off into SECRETORY VESICLE
- Fuses via exocytosis and exits cell and fuses into bloodstream
Where do transcription and translation respectively occur?
Nucleus and cytoplasm
What is occurring during transcription?
Genetic info encoded in DNA is copied onto an RNA strand using CBP
Describe the steps of transcription
- RNA polymerase binds to promoter
- RNA nucleotides are added complementary to DNA strand
- RNA polymerase detaches at terminator seq
- Introns in pre-mRNA are cut out (RNA splicing)
- Exons are put together and form mRNA code for prot
What occurs in translation?
mRNA strand is read by a ribosome, which then assembles the appropriate a.a. into a protein
Describes the steps of translation
- initiator tRNA attaches to start codon AUG (methionine)
- large and small ribosomal units join to form a functional ribosome and initiator tRNA fits into P site
- anticodon of incoming tRNA pairs with next mRNA codon at A site
- a.a. on tRNA at P site forms a peptide bond with a.a. at A site
- 2-peptide prot becomes attached to tRNA at A site
- ribosome shifts by one codon (i.e. tRNA at P-site moves to E site and released from ribosome; tRNA at A site now moves to P site
- prot. synthesis stops when the ribosome reaches stop codon on mRNA
In reproductive cell division, what are the chromosome number in the parent and daughter cells?
PARENT - 46 chrom/23 pairs of homologous chrom (diploid)
DAUGHTER - 23 chromosomes (haploid)
What occurs in each phase of interphase?
G1 - organelles are duplicated, centrosome rep begins
S - DNA replicates to produce 2 copies of each chromosome (46 undup chrom to 46 dup chrom)
G2 - cell growth continues, centrosome rep completed
What happens in prophase and how many chromosomes are present?
- chromatin condense into visible chrom
- nucleolus disappears, nuclear env breaks down
*46 dup chrom
What happens in metaphase and where/how many chromosomes are present?
- centromeres line up at metaphase plate (center of mitotic spindle)
- spindle fibers attach to center of each chrom
**46 dup chrom lined up
What occurs during anaphase?
- separation of centromeres
- movement of 2 sister chromatids move toward opposite poles of cell
**46 x 2 undup chrom each moving to opposite sides
What occurs during telophase?
- cleavage furrow appears to separate the cell
- chrom uncoil and revert to chromatin, nuclear env reforms, cell begins to separate
**after separation, 2 daughter cells with 46 undup chrom
What is cytokinesis and when does the process take place?
Division of cytoplasm + organelles into 2 daughter cells
Process begins in late anaphase or early telophase with formation of cleavage furrow
What does meiosis produce?
Production of haploid cells containing 23 chromosomes
How does meiosis I differ from meiosis II?
I - pairs of homologous chrom to single chrom (chrom # reduced by half)
II - from duplicated chrom to unduplicated chrom (chromatids split)
What occurs in prophase I?
Chromosomes arranged in homologous pairs to form tetrads
Crossing-over occurs bt non-sister chroms; tetrads exchange gen mat to reate genetic diversity
What occurs in metaphase I?
Homologous pairs line up along metaphase plate
What is happening in anaphase I and telophase I?
ANAPHASE - members of each H pair separate, with one of each pair moving to opposite poles of cell
TELOPHASE - similar to T1
What is produced after meiosis I?
23 duplicated chromosomes in each resulting cell
What happens in meiosis II and what does it produce?
Similar to mitosis phases; 23 unduplicated chromosomes are produced
What are possible outcomes of a protein’s trafficking in cell, and its corresponding vesicles?
- Transport vesicles bring it from RIBOSOME to GOLGI
- Transfer vesicles pass on protein to secretory/membrane/transport v
- a. Secretory vesicles allow it to exit cell via exocytosis
b. Membrane vesicles allow it to enlarge membrane
c. Transport from GOLGI to LYSOSOME
What is the function of peroxisomes?
oxidizes a.a. and FA
detoxifies H2O2, alcohol, and other harmful substances
What is the function of proteasomes?
degrades damaged/faulty proteins by cutting them into peptides
