animal cell structure and function Flashcards
list the components of the cell
- nucleus
- nucleolus
- nuclear envelope with nuclear pores
- chromatin
- lysosome
- smooth endoplasmic reticulum
- rough endoplasmic reticulum
- ribosome
- mitochondria
- golgi body
- cytoplasm
- plasma membrane
what is the structure of the nucleus?
- nuclear membrane with nuclear pores
- nucleolus
- chromosomes
- nucleoplasm
what is the function of the nucleus?
contains DNA and is the site of DNA replication and transcription
what is the function of the nucleolus?
synthesis of ribosomal RNAs (rRNAs)
what is the function of a ribosome?
site of protein synthesis
what is the structure of a ribosome?
- complex of proteins and rRNAs
- 2 subunits (large and small)
where are bound ribosomes located?
endoplasmic reticulum
where are the free ribosomes located?
cytoplasm
what is the structure of the endoplasmic reticulum?
- continuous membrane system of flattened tubes (cisternae)
- rough ER is studded with ribosomes
- smooth ER has no ribosomes
what is the main function of the rough ER?
protein synthesis on ribosomes
where do newly synthesized proteins go?
- accumulate in the ER
- then packaged into membrane bound vesicles
what is the function of the golgi apparatus?
post translational modifications of proteins
what are the post translational modifications?
- formation of disulfide bonds
- addition and processing of carbohydrates
- specific proteolytic cleavages
- assembly into multimeric proteins
- proper folding of the protein
list the steps of the ER-Golgi secretory pathway
- proteins for export are synthesized in the rough ER
- proteins are then packaged into transport vesicles that ‘bud off’ from the rough ER
- the vesicles then fuse with the golgi (cis face) and transfer proteins into the golgi lumen
- secretory vesicles then bud off from the golgi (trans face) and fuse with the plasma membrane for release of proteins (exocytosis) while some proteins are kept for the cell
what is the function of the mitochondria?
they are essential for energy production; harness ATP from the oxidation of food molecules
which metabolic pathways occur in the mitochondria?
- oxidative phosphorylation
- electron transport chain
- krebs cycle
what is the structure of the mitochondria?
- outer membrane
- inner membrane (cisternae)
- inner membrane space between inner and outer membrane
what are lysosomes?
organelles involved in degradation of molecules and waste
what is the structure of a lysosome?
lipid bilayer membrane with degradative enzymes
what do the lysosomal degradative enzymes degrade?
- proteins
- nucleic acids
- carbohydrates
- lipids
what is the function of the cytoskeleton?
provide the cell with shape and structure - dynamic not rigid
what are the three structures that comprise the cytoskeleton?
- microfilaments
- microtubules
- intermediate filaments
what is the structure and function of a microfilament?
- polymers of actin
- give the cell flexibility
- microfilaments can be modified during cell movement (migration, endo/exocytosis)
what is the structure and function of a microtubule?
- polymers of tubulin
- provide the cell with shape
- important for mitosis/meiosis where chromosomes attach to microtubules via centromere
what is the function of intermediate filaments?
mainly structural function
what is the structural basis for all animal cell membranes?
lipid bilayer
what is the composition of the plasma membrane?
~ 50% lipid
~ 50% protein
what are the 3 main classes of membrane lipids in animal cells?
phospholipids - majority
cholesterol - 15%
glycolipids- 5%
what is the function if cholesterol in the plasma membrane?
provides rigidity to the membrane
which factors control the fluidity of cell membranes?
- length of fatty acid chains
- degree of saturation
- cholesterol content
what are the different types of phospholipid movements?
- lateral diffusion
- flip-flop (very rare)
- rotation
- bobbing
what is lateral diffusion in phospholipid membrane?
phospholipids move from one part of the membrane to another - only on the same side
what is flip-flop movement in the phospholipid membrane?
phospholipid movement from one side of the membrane to the other - very rare and requires specialized enzymes
what is rotation in the phospholipid membrane?
each phospholipid can rotate in its place
what is bobbing in the phospholipid membrane?
each phospholipid can bob up and down in the same position
what are integral proteins?
proteins that extend through the lipid membrane and consist of both hydrophobic and hydrophilic domains
- very strong interactions with the membrane
what are peripheral proteins?
proteins are bound indirectly to either face of the phospholipid bilayer
- weak interactions with the membrane
what are the types of transport through the lipid membrane?
- passive diffusion
- facilitated diffusion
- active transport
- endo/exocytosis
what is passive diffusion?
transport of molecules into the cell without the need for energy
what is facilitated diffusion?
transport of molecules into the cell via transport proteins
what is active transport?
transport of molecules into the cell which requires energy in the form of ATP and transport proteins
what is endo/exocytosis?
form of transport where the plasma membrane undergoes remodeling to either engulf (endo) or expel (exo) molecules
