Topic 3: Cell structure Flashcards
compare the structure of bacterial and eukaryotic cells
Both have DNA, ribosomes, cytoplasm, plasma membrane. Bacterial: unicellular eukaryotic: multicellular or unicellular. Eukaryotic cells tend to be larger than most prokaryotic cells. Prokaryotic cells have no nucleus to contain their DNA (free floating in nucleoid instead, DNA is not surrounded by membrane), no membrane bound organelles (nucleus, mitochondria, ER, Golgi.)
explain the endomembrane theory and the evolution of eukaryotes.
The plasma membrane of an archaean (prokaryote) ancestor invaginated (folded in). The internal membranes separate from the plasma membrane. And the organelles of the endomembrane system evolved overtime creating diversity of organelles.
list the organelles of the endomembrane system.
the endoplasmic reticulum, golgi complex, endosomes, lysosomes, vesicles, vacuoles. (GLEVVER)
describe the structure of the endomembrane system.
A series of discrete and dynamic membrane bound spaces.
what is the function of the endoplasmic reticulum, specifically smooth vs rough.
biosynthesis of macromolecules. Smooth: lipid, and carbohydrates synthesis, also stores calcium. Rough: protein synthesis, transport vesicles.
golgi function
Processes, and modifies ER product (received from cis side) (fixes mistakes made in ER.) Then ships vesicle secreting it from the trans face and moving to appropriate destination
What is the function of the lysosomes?
Lysosomes have digestive enzymes. Digest food through phagocytosis, in food vacuoles. Occurs by fusion of lysosome to food vacuole (from outside cell coming in), and release of enzyme (to digest). They also recycle old organelles through autophagy. The lysosome fuses with a vesicle that has peroxisome. (vesicle already within cell).
explain the endosymbiont theory and mitochondria and chloroplast.
The theory states that mitochondria and plastids (chloroplasts and related organelles) were formerly prokaryotes living within larger host cells. The evolution of mitochondria in eukaryotes. Organisms involved early eukaryote, heterotrophic bacteria, phagocytosis didn’t work so the bacterium survived. A mutualistic relationship eventually develops: the bacterium gets a home and becomes the mitochondria so that the eukaryote gets more efficient energy.
outline the evidence supporting the endosymbiont theory.
Eukaryote inner membranes are similar to plasma membranes of prokaryotes, division and DNA structure are similar in these organelles and prokaryotes, these organelles transcribe and translate their own DNA, their ribosomes are more similar to prokaryotic than eukaryotic ribosomes
compare the structure and basic function(s) of the three cytoskeletal elements.
Microfilaments: actin proteins, support cell shape in animals, control movement within cytoplasm in plants, control cell movement (amoeboid movement). Intermediate filaments: various fibrous proteins reinforce cell shape (intermediate filaments are stronger than microfilaments). Microtubules: (tubes, biggest filaments), grow and shrink at one end, support cell shape, locomotion (flagella and cilia), cellular trafficking (movement in cell). All movement in cell controlled by microtubules.
describe the four types of cellular junctions.
Adhesion: tight and anchoring junctions, help with attachment, holding cells together.
Communication: gap junctions, plasmodesmata (bridges between cytoplasm, cell wall, interstitial space.
describe the limitations to cell size based on the surface area to volume ratio
Cell needs to be large enough to hold machinery and small enough to be efficient
