Module 2: Inside the Cell Flashcards
What is the structure of the cell membrane?
Two rows of molecules with glycerol heads (facing outwards and hydrophilic) and two glycerol tails (facing inwards and hydrophobic). The chain is also imbedded with proteins and changes depending on what must be transferred in and out of the cell
What is the function of DNA?
Forms inherited genetic material
What is the function of RNA?
Relays instructions from genes to guide synthesis of proteins from amino acids
What is DNA made of?
Nucleotides consisting of a nitrogenous base (ATCG), phosphate group and a pentose sugar.
What is the fluid mosaic model?
A model of the plasma membrane where the PM is a sea of fluid lipids with floating (iceberg) proteins.
What are the two classes of membrane protein?
Integral (extends into/through the membrane. Most are transmembrane)
Peripheral (not firmly embedded, attached to polar heads)
What are the stabilizing bonds in DNA?
Phosphodiester bonds (links sugar to phosphate) H bonds (links opposing nucleotides together)
What are the six different types of membrane proteins?
Ion channels, carriers, receptors, enzymes, linkers, cell identity markers
What are ion channels?
Form a pore which specific ions can cross. Most have several for different ions (integral)
What are carrier proteins?
Transport substances across membrane by changing shape. Requires ATP/ Allows polar substances through the membrane or against diffusion gradient. (integral)
What are receptors?
Serve as recognition sites. They relay information to cell interior, usually a ‘signal cascade’. They bind to a specific molecule called a ligand (integral)
What are enzymes?
Catalyse reactions in or outside cell. (integral and peripheral).
What are linkers?
Anchor filaments inside and outside the cell to gives stability and shape. Can also bond to proteins of PMs in neighbouring cells to link together. They bond to intermediate filaments in the extracellular matrix (integral and peripheral.
What are cell identity markers?
Also known as glycoproteins. They allow cells to recognize each other during tissue formation, or by recognizing foreign bodies. (This cell is ME, this cell is NOT ME)
What are the benefits of membrane fluidity?
Allow mobility and structure, self repair if punctured
What is an electrical gradient?
Difference in electrical charge between two areas. Across the membrane this is called membrane potential.
Describe prokaryotic cells
cytoplasm with PM, no nucleus or membrane bound organelles, have ribosomes, DNA is in circular chromosomes,
Describe eukaryotic cells
Cytoplasm with PM, nucleus and membrane bound organelles, ribosomes, Linear DNA
What is the structure of the nucleus?
Enclosed by a double lipid bilayer (nuclear envelope) and lined with nuclear lamina. Continuous with rough ER. Has nuclear pores for materials entry/exit. Dark centre is the nucleolus
What is the function of the nucleus?
House/protect DNA. RNA/ribosome production. Allow molecules to be separated where necessary- eg enzymes and substrates
What is the structure of the ribosmes?
Two subunits (large and small). Made of RNA and rRNA. They are made separately in the nucleolus and can be attached to ER or free.
What is the function of the ribosome?
On ER = make proteins for secretion, insertion into membrane or specific organelles.
Free = make proteins used in cytosol
What is the structure of rough Er?
Continuous with the nuclear membrane. Folded into flattened sacs. Studded with ribosomes
What is the function of Rough ER?
Site of protein synthesis