Unit 2 part 4 Flashcards
Cell structure
Cell structures that are not considered organelles
- Cell wall -> an extracellular structure
- Cytoplasm -> gel like fluid spread throughout the cell, does not have compartmentalized structure
- cytoskeleton -> Found throughout cell, does not have a compartmentalized structure
Plasma membrane
A phospholipid bilayer that surrounds and encloses cell
- Controls what enters and exits the cell
- Conisdered an organelle (by IB) tho is not a subcellular structure
Cell fractionation
A process that separates cell organelles while preserving functions
- Preparing cells for ultracentrifugation
Steps for cell fractioning
- Homogenization
- Tissue that cells are broken up in a blender. Cells are blended in cold, buffered, solution that is isotone to cytoplasm of cells - Blended solution then filtered to remove large cell debris
Ultracentrifugation
Uses fast centrifuge to separate cell organelles according to density
Steps for ultracentrifugation
- Filtered solution that has the cell organelles is spun at low speed by an ultracentrifuge
- The densest organelle, the nucleus, forms a pellet at bottom of centrifuge tube
- Pellet is removed, process is then repeated at faster speed resulting in a series of pellets containing one type of organelles each time
What is stored in the nucleus?
Eukaryote’s chromosomes are stored in nucleus. Their genetic info is stored in form of DNA for growth and develeopment
How are chromosomes transcribed
Chromosome genes are transcriped into mRNA w/in nucleus
- mRNA leaves nucleus to be translated into polypeptides by ribosomes
How is DNA protected?
DNA is protected in the nucleus from potentially harmful reactions in cytoplasm
Transcription of DNA
Process of transcription of DNA to mRNA occurs in the nucleus and DNA is modified before entering cytoplasm
Translation and transcription in prokaryotes
Prokaryotes don’t have a nucleus meaning there is no separation of the process of transcription and translation
outer membrane (mitochondria)
channels for pyruvate to enter Mitochondrion, b/c it contains protein channels and is not permeable to protons, allowing concentration of protons to build up in intermembrane
Lysosomes
Membrane bound organelle which contain digestive enzymes
Inner membrane
Contains proteins of electron transport chain and ATP syntheses
- Has proton channels and ATP synthase, the protons give energy for ATP synthesis to go from ADP -> P -> ATP
What is the main function of lysosomes?
Digestion of macromolecules w/in cell
What are digestive enzymes w/in a lysosome capable of doing?
Digesting other cell components and are kept separate from cytoplasm and other cell structures by membrane surrounding lysosomes
What happens when a cell is damaged?
Enzymes are released from lysosomes resulting in digestion of cell
How is a phagosome formed?
Lysosomes fuse w/ the phagocytic vacuole and the lysosome’s enzymes digest the bacterium
Mitochondria
Organelles that produce ATP through aerobic respiration and are recognizable on electron micrographs by its folded inner membrane forming cirstae
What is phagocytosis?
Process by which solid materials like bacteria are taken into a cell by endocytosis
Adaptations of mitochondria
- outer membrane
- inner membrane
- inter membrane
- cristae
- chromosomes
Inter membrane (mitochondria)
Small space allowing rapid accumulation of protons
Cristae (mitochondria)
Many folds in inner membrane and increases surface area
Chromsomes (mitochondria)
Singular circular chromosome that contains genetic info to make all proteins
- Synthesizes proteins required for aerobic respiration
Matrix (mitochondria)
Has DNA ribosomes and all enzymes involved in link reaction and Krebs cycle
Chloroplast
Organelles that carry out photosynthesis in plants + algae
Photosynthesis
Production of organic compounds and absorbs light energy with water and carbon di
Adaptations of chloroplasts
- Thylakoid membrane
- Thylakoid space
- Stroma
- Chromosome
- Enzymes
Thylakoid membrane
Contains chlorophyll for absorption of light, electron transport chain, and ATP synthesis
- Folded nature of thylakoid membrane increases surface area for absorption of light
Thylakoid space
Small space w/in Thylakoid spaces (lumen) that allow for rapid build up for protons
Stroma
Contains a chromosome, 70s ribosomes and all enzymes required for Calvin cycle
Enzymes
All enzymes needed for Calvin cycle found in stroma chloroplast
Nuclear membrane
Nucleus has double membrane w/pores
- Membrane separates production of mRNA in nucleus from cytoplasm
- mRNA is too large to pass through nuclear membrane and enters cytoplasm through nuclear pores
Ribsomes
Synthesizes polypeptides (proteins) by translating mRNA
What are ribosomes composed of
- Large ribosomal subunit
- Small ribosomal subunit
- Both subunits composed of protein and mRNA
Ribosomes and Rough ER
Ribs can be floating around in cytoplasm or attached to rough er
- Freeloaders synthesize proteins to be used in cells
- Attached synthesized proteins to be transported out of cell or for production of lysosome enzyme
membrane of rough er
An extension of nuclear membrane + covered in ribosomes
- proteins made by ribosomes are attached to rough er enter the lumen
- proteins are packaged into vesicles that are transported to the golgi apparatus
Golgi apparatus
Located in between rough er and plasma membrane and is composed of flattened sacks
cisternae
Flattened sacks in golgi apparatus
What happens to vesicles that have protein from rough er?
They move and fuse w/ golgi apparatus
- Then are modified and packaged into secretory vesicles
- Secretory vesicles move towards plasma membrane and secrete protein by exocytosis
Vesicles
Composed of phospholipid Bilayer and transports material around cell
What is sometimes involved in forming some vesicles that transport a specific molecule?
A protein called clathrine
Clathrine
Triskelion shaped protein that is attached to recruiter proteins in a membrane which forms vesicles
What does a clathrine do?
Polymerizes to form a clathrine cage, forcing membrane to form a rounded bud
- Bud is then cleaved off to form a clathrine coated vesicle
- then clathrine cage is removed
