A&P: Cellular Level of Organization Flashcards
Cytoplasm
cellular contents between plasma membrane and nucleus (Cytosol and Organelles)
site of all intracellular activities except those in the Nucleus
Cytosol
composed of water, solutes, suspended particles, lipid droplets, glycogen granules
fluid which many of cell’s metabolic reactions occur
Cytoskeleton
network of protein filaments: Microfilaments / Intermediate Filaments / Microtubules
Microfilaments
composed of actin and myosin
generate movement (muscle contraction, cell division, cell locomotion)
provide mechanical support (anchoring of integral proteins in plasma membrane and core for Microvilli)
Microvilli
contains core of Microfilament
increase surface area for increased absorption
common in small intestine
Intermediate Filament
stabilize positions of organelles and cell-to-cell; other parts of mechanical stress
Microtubules
composed of tubulin
determine cell shape
fx in movement of organelles, chromosomes, entire cells
Cilia and Flagella
Organelles
specialized structures in cells (like organs in our body)
Centrosome
Microtubule organizing center
2 Centrioles and Pericentriolar Matrix
Centrioles
cylindrical structure of Microtubular triplets x 9 in circle
Pericentriolar Matrix
cloud of tubulin, surrounding the 2 Centrioles in Centrosome
Cilia
hairlike projections from cellular surface that contains 20 microtubules and basal body
moves fluids along cell’s surface (like oar)
Flagellum
Cilia-like in structure
moves entire cell
Ribosome
sites of protein synthesis
composed of 2 subunits, made separately in nucleolus
free synthesizes proteins utilized in cytosol
attached synthesizes proteins meant to be sent to plasma membrane or out of cell
Endoplasmic Reticulum
membranous network of flattened sacs/tubules
Rough vs Smooth
Rough ER
synthesize glycoproteins and phospholipids, which are to be transferred to cellular organelles, plasma membrane, or secreted out
Smooth ER
synthesize fatty acids and steroids, NOT proteins
Liver: detoxes lipid-soluble drugs / harmful substances
Liver, Kidney, Intestines: removes phosphate group from glucose-6-phosphate; releasing glucose into bloodstream
Muscle Fibers: stores and releases Ca+2 for contractions
Golgi Complex
prepares most of proteins synthesized by Rough ER Ribosomes for send off
consists of 3-20 Saccules
Cisternae
single unit / “stack” of Golgi Complex
Entry (cis) Face of Cisternae
receives and modifies proteins received from R ER
Exit (trans) Face of Cisternae
modifies, sorts, and packages into vesicles for transport to destinations
Intermediate Saccules
stacks of Saccules in between the cis & trans faces
modify proteins to form glycoproteins, glycolipids, or lipoproteins
Secretory Vesicle / Membrane Vesicle / Transport Vesicle
Vesicles from Golgi Complex meant for:
exocytosis / insertion in plasma membrane / some other destination within the cell(ex. Lysosome)
Plasma Membrane
cell’s outer surface with selective permeability
composed of phospholipid, cholesterol, glycolipid, and membrane proteins
amphipathic
Processing and Packaging of Proteins by Golgi Complex
- Synthesized proteins from R ER arrives in transport vesicle
- Transport vesicle merges with the cis face of GC and releases content into lumen
- Proteins move into Intermediate Saccules. Proteins are modified into glycoproteins, glycolipids, and lipoproteins
- Moves further in depending on the needs
- At trans face of GC, further modified and put into specific vesicles
- Some leave the cell thru exocytosis; some are inserted into plasma membrane; some are transported to Lysosome
Lysosome
membrane enclosed vesicles formed from Golgi Complex that contains digestive enzymes
digests contents of endosome/phagosome/vesicles from Bulk-Phase Endocytosis
carry out Autophagy, Autolysis, extracellular digestion (sperm entering oocyte)
Autophagy
digestion of worn-out organelles
involved in cellular differentiation, growth control, tissue remodeling, environment adaptation, cell defense
Autophagosome
vesicle from ER that contains worn-out organelle during Autophagy
Autolysis
destruction of entire cell by Lysosome
Peroxisome
oxidizes amino acids and fatty acids during metabolism
contains and detoxifies harmful byproduct from metabolism (H2O2 and free radicals)
able to self-replicate
Proteasome
destroys unneeded damaged faulty cytosolic proteins into smaller peptides
Mitochondria
“powerhouse”
generates ATP thru aerobic respiration
plays important early role in Apoptosis
able to self-replicate
External Mitochondrial Membrane
Outer membrane of Mitochondria
Internal Mitochondrial Membrane
Inner layer of Mitochondria containing Mitochondrial Cristae
Mitochondrial Cristae
foldings of Internal Mitochondrial Membrane
creates increased surface are for chemical reactions of aerobic cellular respiration
Mitochondrial Matrix
central fluid-filled cavity of Mitochondria
contains enzymes involved in aerobic cellular respiration
also contains ribosomes
Apoptosis
orderly, genetically programmed death of a cell
occurs in response to DNA damage, lack of O2 nutrients, increased number of free radicals etc.
Nucleus
controls cellular structure
directs cellular activities
produces ribosomes in Nucleoli
Nuclear Envelope
lipid bilayer that separates Nucleus from Cytoplsam
Nuclear Pores
pores present in nuclear envelope outlined by protein channels
controls movement between Nucleus and Cytoplasm through passive and selective active transport
Nucleoli
cluster of proteins, DNA, RNA
produces ribosomes
of Chromosomes
somatic: 46 chromosomes (23 from each parent)
sex:
Chromosome
highly coiled and folded DNA molecule combined with proteins (ex histone)
Nucleosome
single unit of combined DNA, proteins and some RNA
Chromatin
chains of DNA, proteins, and some RNA
Histones
group of 8 proteins packed into a ball
wrapped around with DNA (twice) to form Nucleosome
Linker DNA
holds each Nucleosomes together in Chromatin
Chromatin Fiber
coiled loops of chromatin
Chromatid
condensed Chromatin Fibers just before cell division; replicates to make a pair
Gene Expression
process of gene’s DNA being used to synthesize specific protein
transcription and translation
Base Triplet (from DNA)
sequence of 3 nucleotides in DNA
Codon (of RNA)
specifies a particular amino acid
transcribed from Base Triplet
Transcription
occurs in Nucleus
Base Triplets in DNA serves as template for copying info into codons
3 types of RNA made are: mRNA / rRNA / tRNA
mRNA
Messenger RNA directs the synthesis of a protein; created during Transcription and utilized in Translation
rRNA
Ribosomal RNA joins with ribosomal proteins to make more ribosomes
tRNA
binds to an amino acid and holds it in place on a ribosome for Translation; the amino acid reflects anticodon it has
RNA Polymerase
catalyzes transcription of DNA
attaches to Promoter to start
ends at Terminator
Introns
this region within a gene do not code for parts of proteins
Exons
this region codes for protein segments
pre-mRNA
product immediately after the Transcription; contains both introns and exons
Small Nuclear Ribonucleoproteins (snRNPs)
removes introns from pre-mRNA to produce final product of functional mRNA
“snurps” the useless part
Alternative Splicing of mRNA
process of pre-mRNA transcribed from a gene is spliced in different ways to be translated into different proteins
also final products can be chemically altered after Translation (ex. GC)
Translation
mRNA binds to Ribosome to produce amino acid sequence for a protein according to mRNA’s nucleotide sequence
P site (peptidyl)
bind tRNA carrying the growing polypeptide chain
A site (aminoacyl)
binds tRNA carrying the next amino acid to be added to the growing polypeptide
Process of Transcription
- RNA Polymerase attaches to Promoter
- Based on the base triplet, appropriate codons are formed on the RNA strand
- Ends at the special nucleotide sequence called Terminator, creating pre-mRNA
- snRNPs cuts off introns and splices exons together, creating functional mRNA
Process of Translation
- mRNA molecule binds to small ribosomal subunit
- tRNA (initiator) binds its anticodon to the codon of mRNA
- Large ribosomal subunit attaches to the small subunit, creating functional ribosome
- The initiator tRNA fits in P site of large subunit
- Next tRNA with appropriate anticodon and its amino acid comes and fits into the A site
- Amino acid of P site moves over to A site and bonds with amino acid of A site (peptide bond)
- Ribosome shifts mRNA by one codon; the initiator tRNA is now in E site and is detached
- This goes on until a stop codon reaches A site; created protein will then detach from the final tRNA
- Ribosome units splits apart
Polyribosome
Ribosomes attached to same mRNA for translation
Cell Division
process of cell reproduction
Somatic Cell
any cell of the body other than a Germ Cell
diploid (2n) cells
Germ Cell
gamete (sperm or oocyte) or any precursor cell destined to become a gamete
gametes are haploid (n) cells
Somatic Cell Division
Mitosis and Cytokinesis
Reproductive Cell Division
production of gametes, Meiosis
Cell Cycle
orderly sequence of events in which a Somatic Cell duplicates contents and divides in two
Interphase (G1 / S / G2) and Mitotic Phase (Mitosis: PMAT and Cytokinesis)
Homologous Chromosomes
homologs
2 chromosomes that make up each pair
contains similar genes arranged in same* order
Sex Chromosomes
female = X X
male = X Y
Interphase
G1: cell metabolically active; duplicates organelles and cytosolic components; centrosome replication starts
S: DNA replication
G2: cell growth continues; enzymes, proteins are synthesized; centrosome replication complete
G0 phase
describes cells, like most nerve cells, that were destined to remain in G1 or never divide again
Mitotic Phase
Mitosis and Cytokinesis
results in formation of 2 identical cells
Mitosis
Nuclear division
PMAT
Prophase
chromatin fibers coils up and condenses to form chromosome (consists of 2 identical chromatids)
tubulins in Pericentriolar Matrix of now 2 Centrosomes (replicated during interphase) starts to form Mitotic Spindle
Nucleolus disappears and nuclear envelope breaks down
Centromere
central region that holds the 2 Chromatids together in Chromasome
Kinetochore
protein complex that covers centromere
Mitotic Spindle
football shaped assembly of microtubules that attaches to Kinetochore
Metaphase
Mitotic Spindle align Centromeres of Chromatid pairs at the Metaphase Plate (center)
Anaphase
Chromosomes are split into 2 Chromatids (still termed chromosomes) towards each poles
Telophase
Chromosomes stops moving and revert to Chromatin form
Nuclear Envelope forms around each Chromatin mass
Nucleoli reppaers
Mitotic Spindle breaks up
Cytokinesis
division of cell’s cytoplasm and organelles into 2 identical cell
Cleavage Furrow
indentation of plasma membrane formed during late Anaphase and completed in Telophase
a contractile ring is formed by Actin Microfilament that pulls plasma membrane inward
Cyclin-dependent Protein Kinases (Cdk’s)
transfers phosphate group from ATP to a protein for its activation
crucial in initiation and regulation of DNA replication, Mitosis, Cytokinesis
Cyclin
responsible of switching Cdk’s on and off
level rises during G1, S, G2 to push into Mitosis and declines after Mitosis
Necrosis
cell death by pathological cause
causes inflammatory response by immune system (unlike apoptosis)
Meiosis
reproductive cell division occurring in gonads
divided into 2 separate stages
Synapsis
pairing-off of sister chromatids during Prophase I of Meiosis I, forming Tetrad
Crossing-Over
exchange between parts of two non-sister chromatids, resulting in Genetic Recombination
Telomere
specific DNA sequences at tips of chromosomes
protects erosion; prevents sticking with one another
wears out with each division and may cause some loss of chromosomal material
