Cell Structure & Organisation Flashcards
What is a prokaryotic cell?
DNA not within nucleus, smaller, no membraned cell organelles (eg. bacteria)
What is a eukaryotic cell?
DNA bound in nucleus, bigger, has endomembrane system with cell organelles (eg. animal/plant cells)
What cell organelles contain DNA?
Nucleus, chloroplasts, mitochondria (absent in prokaryotes)
What is the protoplasm?
Cytoplasm and cell organelles/nucleus
What is an endomembrane system?
Anything made out of membrane (cell organelles)
What do prokaryotic and eukaryotic cells have in common?
The presence of cell membrane, cytoplasm, ribosomes, chromosomes
Why are cells so small?
To increase SA:V ratio, increase rate of diffusion of materials in and out cell
What can be seen under the light microscope?
Nucleus, cell membrane, cytoplasm, cell wall, vacuole, chloroplasts
Cell structures in both animals and plant cells
Nucleus (+ nuclear membrane and nucleolus), mitochondria, cytoplasm, cell membrane, RER and SER, ribosomes, Golgi body, lysosomes
What is the cell wall made out of?
Cellulose (multiple layers of the polysaccharide)
What does the xylem transport?
Water, mineral ions
What does the phloem transport?
Sucrose (sugar) and amino acids
What are the storage carbohydrates of animal and plant cells?
Glycogen and starch respectively
What cell organelles are double-membraned?
Nucleus, ribosomes, chloroplasts (same as those with DNA)
What are nuclear pores?
Protein-lined channels that let mRNA out of nucleus to the ribosomes
What is the nucleoplasm?
Nucleus’ cytoplasm
What are chromosomes made of and where are they stored?
They are DNA wrapped around histone proteins and are stored in the nucleus
How are histone proteins made?
Translated by ribosomes in the cytoplasm and re-enter the nucleus via nuclear pores to form chromosomes
What happens inside the nucleolus (within nucleus)
Ribosomes’ subunits (components) are stored here and ribosomes are assembled here, leaving the nucleus via nuclear pores to the rest of the cell
What is the Fluid Mosaic Model?
The phospholipid bilayer of the cell membrane is described as fluid because the phospholipid molecules are able to move freely and laterally, and mosaic because protein molecules are randomly embedded or scattered about
What is cytoplasm made of?
90% water, 10% dissolved solutes
What is a tonoplast?
The membrane of a plant cell vacuole
What are endoplasmic reticulum?
Membranes continuous with the nuclear membrane, rough (with ribosomes) or smooth (without ribosomes)
What is the endoplasmic reticulum’s inner space known as?
Endoplasmic reticulum lumen
What does the Golgi body consist of?
Stacks of flattened membrane bound bodies known as cisternae
What are ribosomes?
Protein synthesisers (on RER or floating around freely)
Function of the mitochondria (singular: mitochondrion)
Site of aerobic respiration, where chemical energy in food is oxidised and converted into ATP, RELEASES energy
Describe the mitochondria’s membrane
Smooth outside, cristae inside to increase SA for more chemical reactions. Matrix is the inner area within mitochondria with enzymes
What does the SER do
Synthesises fats and steroids, detoxification. More found in liver
Structure of RER and SER
RER: Stacked layers of membrane
SER: cross-sectional tubes
Function of the Golgi body/apparatus/complex
Chemically modifies and packages proteins made by ribosomes on RER, packaged proteins leave in small transport vesicles to leave the cell
What are lysosomes + optimal pH
Small sacs of hydrologic (digestive) enzymes dispersed in cytoplasm, digests bad cell parts. Optimal pH of 5
What is RNA?
Ribonucleic acid, near identical photocopy of DNA, blueprint given to ribosomes to synthesis proteins.
How are proteins synthesised?
DNA is photocopied to make mRNA in the nucleus, which leaves through nuclear pores to the ribosomes on RER to be synthesised. Synthesised proteins go to Golgi body in small transport vesicles to be chemically modified and repackaged, going to final destination in vesicles again.
Definition of tissue
Group of similar cells performing one function
Definition of organs
Different groups of cells working for one function
Definition of system
Several organs working together for a few functions
Which part of a cell has the least oxygen?
Mitochondria, since O2 is used up in aerobic respiration to release energy
