B2.2 Organelles and Compartmentalisation Flashcards
Define organelle
An organelle is a discrete structure within a cell that is adapted for a specific function
List solid organelles and those enclosed by a single membrane and a double membrane.
Ribosomes
Endoplasmic Reticulum
Golgi Apparatus
Lysosomes
Peroxisomes
Vacuoles
Nucleus
Mitochondria
Chloroplasts
Outline the reason why the cell wall, cytoskeleton and cytoplasm are not considered to be organelles.
Cell wall : it is an extracellular structure
Cytoplasm : doesn’t have a compartmentalized structure
Cytoskeleton : doesn’t have a compartmentalized structure
Outline the benefits of DNA in the nucleus being compartmentalized from the cytoplasm.
Gene regulation
DNA protection
DNA organization
RNA processing
List advantages of compartmentalization within cells.
Allows for greater efficiency
Protective environment for specialized activities in the cell
Able to store and use concentrations of metabolites and use enzymes which aren’t compatible with metabolism occurring within the cytoplasm of a cell
Compare the location and timing of initiation oftranscription and translation between prokaryotic and eukaryotic cells.
Transcription and translation occur in the cytoplasm for prokaryotes and have no delay in between
Transcription occurs within the nucleus for eukaryotes before being transported out of the nucleus into the cytoplasm to be translated.
Outline why post-transcriptional modification of RNA is not possible in prokaryotic cells.
Limited occurence of introns, capping enzymes and extensive polyadenylation.
State the meaning “compartmentalization” within cells.
A separate section of structure or container where certain items are kept seperate from others.
Outline the benefit of compartmentalization of lysosomes and phagocytic vacuoles in cells.
Allows for controlled degradation of engulfed material and protection of cellular components.
Describe how the following mitochondrial structures are adapted to their function: outer membrane, inner membrane, intermembrane space, cristae, matrix, ribosome and mtDNA.
Outer membrane : channels for pyruvate to enter miochondrion
Intermembrane space : small space allows for rapid accumulation of protons
Inner Membrane : Contains the electron transport chain to actively transport protons into the intermembrane space
Cristae : Inner membrane is highly folded into cristae to increase the surface of the inner membrane
Matrix : Contains enzymes and metabolites required for the link reaction and Krebs cycle
Ribosomes : allows for localized protein synthesis
mtDNA : possesses it’s own circular DNA
Describe how the following chloroplast structures are adapted to their function: double membrane, thylakoid membrane, photosystems, compact thylakoid lumen, stroma, ribosome and cpDNA.
Double membrane : outer membrane acts as a barrier that protect the organelle, and the inner membrane regulates the transport oof molecules into and out of the chloroplast
Thylakoid membrane : system of interconnected sacs neccesary for light dependent photosynthesis
photosystems : protein complexes embedded in the thylakoid membrane consisting off chlorophyll and captures light energy to transform it into ATP and NADPH
Compact thylakoid lumen : a narrow space within the thylakoid membrane that allows for efficient accumulation of protons during light dependent reactions, creating a proton
Stroma : fluid filled region in the chloroplast provinding a suitable enviroonment for enxymatic reactions such as carbon fixation
Ribosome : synthesize proteins encoded by chloroplast DNA, is involved in photosynthesis
cpDNA : circular DNA allowing localized gene expression and proteinn synthesis
Describe the structure and function of the pores in the nuclear membrane.
Protein complexes that regulate the exchange of molecules between the nucleus and the cytoplasm in eukaryotic cells.
Describe the breakdown and reformation of the nucleus during mitosis.
The nucleus breaks down as the nuclear envelope disassembles, allowing for chromosome segregation, and reforms after cell division is complete.
Outline the structure of ribosomes.
Large ribosomal subunit and small ribosomal subunit
Compare the structure and function of free ribosomes and those bound to the rough endoplasmic reticulum.
Free ribosomes synthesize proteins to be used in the cell, ribosomes attached to the RER synthesize proteins to be transported out of the cell
