Ch. 1 Cell and Tissue Function Flashcards
What are the primary components of a eukaryotic cell?
- plasma membrane
- nucleus
- cytoplasm
What is the difference between cytoplasm and cytoplasmic matrix?
cytoplasm liquid in the cell that contains organelles and the cytoplasmic matrix.
cytoplasmic matrix contains solutes and organic molecules like carbs, proteins, lipids, and RNA.
What is in the nucleoplasm?
Enzymes needed for transcription
What proteins are associated with the lipid bilayer?
Integral proteins (span the lipid bilayer and are part of the membrane) -form ion channels Peripheral proteins (bound to one side of the membrane and don't pass into the lipid bilayer) -receptors and intracellular signaling
What is the purpose and structure of the cell coat?
cell-to-cell recognition by way of antigens on the cell (ex: RBCs)
Made of glycoproteins, glycolipids, and lectins (carb binding proteins).
What is the function of the nucleus?
- Contains DNA
2. Synthesis site of RNA (transcription), which moves to the cytoplasm
What are the 3 types of RNA?
- mRNA - copies and carries DNA instructions for protein synthesis to the cytoplasm
- rRNA - where proteins are made (ribosomes!)
- tRNA - transports aa’s to ribosomes to be incorporated into protein being made
What is chromatin?
structure of DNA and proteins in the nuclear matrix
condensed = inactive = heterochromatin
Extended = active = Euchromatin (all start with vowels)
What does the nucleolus do?
the site of rRNA synthesis and some ribosome creation
What allows selective transport into and out of the nucleus?
nuclear pore complexes on the nuclear envelope
What types of proteins do ribosomes create depending on location?
Free ribosomes = create proteins that remain in cell for cytoplasmic structure or function
Ribosomes attached to ER = translate mRNAs that code proteins that bind to membranes or leave the cell
What does the rough ER do?
contains ribosomes that synthesize proteins that will be part of cell membrane, used to make lysosomal enzymes, or secreted.
What does the smooth ER do?
NO protein synthesis (no ribosomes = no proteins)
- enzymes in ER make lipid and steroid hormone molecules
- regulates intracellular calcium
- metabolism of hormones and drugs
What are 2 examples of a smooth ER in body systems?
- sarcoplasmic reticulum of muscle cells: store calcium ions for muscle contraction
- liver = smooth ER stores glycogen and metabolizes lipid-soluble drugs
Function of the Golgi apparatus
Products of the ER are transported here in vesicles where they are modified and packaged into secretory granules/vesicles.
Also makes big carbs, which are added to proteins from the rough ER to make glycoproteins (part of cell membrane!)
How does insulin relate to the Golgi apparatus?
Insulin is secreted in a large, inactive form from the ER and is broken by the GA of beta cells in the pancreas into smaller active insulin molecules.
What pathways are used for lysosomal degredation?
- small extracellular proteins form endocytic vesicles after entering the cell by pinocytosis or receptor-mediated endocytosis
- large extracellular particles like bacteria and debris are engulfed by phagocytosis and phagosome fuses with a lysosome.
- Autophagy: intracellular particles like organelles are engulfed and fuse with a lysosome.
What is lysosomal storage disease?
A type of lisosomal enzyme is absent or inactive, so digestion of some substances cannot occur and they accumulate in the cell
What is an example of a lysosomal storage disease?
Tay-Sachs disease
- hexosaminidase A is absent.
- GM2 ganglioside (in nerve cell membranes) accumulates in the nervous system and retina (mainly).
What do peroxisomes do?
contain enzymes used in oxidative reactions to degrade free radicals like hydrogen peroxide
- also break down long chain fatty acids (important in liver cells to form bile acids)
What do proteasomes do?
break down misfolded proteins in a process called ubiquitination.
How are mitochondria self replicating?
They contain their own DNA and ribosomes
- DNA encodes rRNA and tRNA needed to make proteins for use by the mitochondria
How do mitochondria regulate apoptosis?
They release molecules such as cytochrome c into the cytoplasm, which binds an apoptosis inhibitor and induces apoptosis
- apoptosis dysregulation may be an issue with cancer and neurodegenerative diseases.
How is mitochondrial DNA inherited?
Matrilineally
Where does the anaerobic glycolytic pathway occur?
cytoplasm
Where does the aerobic pathway occur?
mitochondria
Why is ATP the energy currency of the cell?
When ATP is hydrolyzed into ADP or AMP (loses 1-2 phosphate groups), a lot of energy is released for use (metabolism of food molecules provides ATP)
What is glycolysis?
Conversion of glucose into pyruvic acid, with yield of 2 ATP per glucose, in anaerobic environment (first few minutes of exercise)
What happens to pyruvic acid if there is no aerobic environment, like in cardiac arrest?
Pyruvic acid is converted to lactic acid, which moves out of cells into the extracellular fluid
What is the citric acid cycle?
pyruvic acid enters the mitochondria and combines with acetyl-coenzyme to form acetyl-coA.
oxidative reactions involving NADH and FADH release CO2 and 2 ATP.
fatty acids and amino acids can also enter the citric acid cycle
What is the electron transport chain?
Electrons generated from glycolysis and the citric acid cycle, carried by NADH and FADH2, are oxidized in a series of reactions on the inner mitochondrial membrane. This produces a large amount of ATP (32 for 1 glucose) and H20
What is a ligand?
molecules with a high affinity for receptors
what are G Protein-linked receptors?
regulatory proteins that bind to GDP and GTP
What do G Protein-Linked receptors do?
- Hormone (first messenger) binds receptor
- Activated receptor interacts with G-Protein linked GDP
- G protein subunits dissociate
- alpha subunit of G protein activates a protein to catalyze ATP to cAMP (second messenger)
- Second messenger activates internal effector
- Cell response
Enzyme-linked receptors
Integral proteins with ligand-binding sites on outer surface of cell membrane. Binding of hormone to receptor activates enzyme, which catalyzes formation of cAMP (second messenger)