Lecture 3 Flashcards
Prokaryotic and Eukaryotic Cell Structure
True or false: Prokaryotes lack membrane bound organelles
True
Cytoplasm
Aka cytosol; a semifluid material inside the cell membrane. Makes up the majority of the cell
What is cytoplasm made of?
70-80% water; mix of organic ions, solutes, free amino acids, carbohydrates, proteins
What type of reactions take place in the cytoplasm?
Enzymatic reactions- since prokaryotic cells lack membrane-bound organelles, most biochemical reactions occur in the cytoplasm
Nucleoid
Region where prokaryotic DNA is organized into a single, circular chromosome. This region also contains some RNA and proteins
Which form of DNA is essential for viability of bacteria?
Chromosomes
Plasmids
Extra chromosomal DNA elements that are smaller than chromosomes. These can replicate on their own, so can be passed onto daughter cells. Used in genetic engineering
What is the purpose of plasmids in bacteria?
Enhances virulence of certain bacteria, can mediate antibiotic resistance, tolerance to toxic metals
True/ false: Plasmids are essential for viability of bacteria
FALSE
Ribosomes
made of RNA and protein (ribonucleoprotein complex)
How do ribosomes build proteins?
They link amino acids (site of translation of mRNA into proteins)
What are the two subunits of Prokaryotic 70S ribosomes?
1) Large subunit (50S)
2) Small subunit (30S)
True/ False: Ribosome function is essential for cell viability.
True
What is an effective target for antibiotics?
Bacterial ribosomes, since these are essential for cell viability.
Some bacterial species make BLANK to survive harsh conditions.
Endospores
Endospores
Aka bacterial spores, these are metabolically inactive structures that allow certain cells to enter a dormant state
Characteristics of endospores
Highly resistant to environmental stresses such as starvation, heat, drying, radiation
When conditions become favorable, what happens to spores?
They germinate back into vegetative cells
Sporulation
The process of forming an endospore
What are the 2 clinically important spore-forming bacteria genera?
Bacillus and Clostridium
Examples of medically relevant species that make endospores
clostridium tetani (tetanus), clostridium botulinum (botulism), clostridium perfringens (gas gangrene), clostridium difficile (severe diarrhea), bacillus anthraces (anthrax)
True/ false: Endospores survive for extended periods on surfaces, even in healthcare facilities
True
Intracellular structures exist within the confines of what:
Plasma membrane
Prokaryotic cytoskeleton
Made of proteins that resemble eukaryotic actin and tubular; this aids in cell organization, coordinates cell division, and supports cell shape
Inclusion bodies
Used by prokaryotes to store enzymes, iron, glycogen, and poly-B-hydroxybutyrate
Endosymbiotic Theory
Series of sequential, cell-merging events between an ancient eukaryotic ancestor and certain prokaryotes
What two organelles support the endosymbiotic theory?
Chloroplast and mitochondria
What did mitochondria evolve from?
engulfed non-photosynthetic prokaryotes
What did chloroplast evolve from?
Engulfed photosynthetic prokaryote (e.g. cyanobacterium)
Abundant evidence supports the endosymbiotic theory, with mitochondria and chloroplasts having…
their own circular DNA, 70S ribosomes (similar to bacteria), double-membrane structures, similar size to bacteria, ability to replicate by a process similar to binary fission, genes resembling certain bacterial genes
All eukaryotic cells have a BLANK that acts as a selective barrier.
Plasma membrane
Structure of eukaryotic plasma membrane
Phospholipid bilayer with many sterols- eg cholesterol to regulate membrane fluidity
True/ False: All eukaryotes have a cell wall
False: only fungi, plants, and certain protists have cell walls
What are cell walls made of?
Chitin or cellulose polymers, these do not have peptidoglycan!
Nucleus
Double membraned organelle housing the nucleic acids of the cell. This is where DNA is converted to RNA (transcription)
How/ where is DNA organized in eukaryotic nucleus?
DNA organized as chromatin in the nucleoplasm
Where is RNA found?
In the dense area of the nucleus called the nucleolus
Process where DNA is turned to RNA
Transcription
How is RNA able to be transported to the cytoplasm?
Through a pore in the nuclear envelope
Ribosomes (eukaryotes)
Essential for making proteins. Made of protein and ribosomal RNA (rRNA). 80S
What are the components of the eukaryotic ribosome?
These are 80S: made up of a small subunit (the 40S subunit) and a large subunit (the 60S subunit)
Do eukaryotic ribosomes have a membrane?
They can be free in the cytoplasm or bound to the endoplasmic reticulum
Eukaryotic flagella
Made of tubular, have a wavelike, back and forth motion
Eukaryotic cilia
Structurally similar to flagella, but they are much shorter and more numerous
Membrane bound organelles
Endoplasmic Reticulum, Golgi apparatus, Mitochondria
Endoplasmic Reticulum
Series of tubes/tunnels linked with nucleus
Rough ER
Studded with ribosomes, site of protein modification
Smooth ER
No ribosomes, lipid production and detoxification
Golgi apparatus
Series of disc-like flattened sacs, modifies cellular proteins, builds lipids, sorts and distributes finished products (post-office of the cell)
Mitochondria
Double-membraned smooth outer membrane, inner membrane with lots of folds (Cristae), makes adenosine triphosphate (ATP, energy molecule) and site of respiration (where oxygen is used)
True/ false: All cells have a plasma membrane
True
Animal cell membranes are made of what:
Cholesterol
Plant cell membranes are made of what:
phytosterols and low levels of cholesterol
Fungi/ protist cell membranes are made of?
A wide variety of sterols, key is ergosterol
What has cell walls?
Eukaryotes only, like plants, fungi, and some protists. Animal cells do not have cell walls.
What direction do eukaryotic flagella move in?
back-and-forth wave-like motion
What direction do cilia move in
oar-like motion
Glycocalyx
