Chapter 7: Inside The Cell Flashcards
Why are cells so small?
the main job of a cell is to take in raw material and get rid of waste through the cell membrane. If a cell gets too large, there is not enough surface area (membrane) to let everything pass.
What are some characteristics of prokaryote cells?
bacteria and archaea, much smaller, no defined nucleus, have ribosomes, have plasma membrane (photosynthetic species have internal membranes), have organelles, and are a part of a multicellular organism.
What are the characteristics of a eukaryote cell?
everything else (plants, animals, fungi, protists), have a true nucleus, are more complex and have a variety of organelles, surrounded by cell membrane, and has ribosomes. Tend to have much more extensive inner membrane systems and larger numbers of intracellular organelles than prokaryotes.
The nucleus is
the command central. It holds most of the cell’s DNA. It is surrounded by the nuclear membrane/envelope which has nuclear pores that control entry and exit and its shape is maintained by nuclear lamina. Nucleolus-synthesis (ribosome production) of rRNA and assembly of ribosome subunits.
Ribosomes are
the protein factories. They carry out protein synthesis via two ways. Free ribosomes = make proteins which will function in the cytosol. Bound ribosomes = make proteins which will be inserted into membranes or secreted - fed directly into the plasma retinum. (Technically not organelles)
Cells with high rates of protein synthesis have a lot of ribosomes like
pancreatic cells.
The endomembrane system is
composed of several different membranes (endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles) and carrie out a variety of functions (proteins synthesis, transport, metabolism, synthesis of lipids, and detoxification of poisons).
The structures of the endomembrane system are grouped together because
the membranes are related either directly continuous or through the transfer of vesicles.
What regions make up the endoplasmic reticulum?
the rough ER (studded with ribosomes) and smooth ER (lacks ribosomes).
What does the smooth ER do?
lipid processing, storage of calcium ions, and detoxification of drugs and poisons.
What does the rough ER do?
proteins destined for secretion, shipped to other organelles or embedded in membrane. Ex: insulin.
Why can you build up a tolerance to drugs and alcohol?
because smooth ER can expand surface area to break it down.
The golgi apparatus
modifies, stores, and ships proteins (also adds a molecular tags like zip codes to proteins bound for secretion). It is made up of stacks of membranous sacs that are not physically connected but allow for products to be transported by vesicles.
Lysosomes are in charge of
waste management. They are membranous sacs of enzymes that digest macromolecules. It does this through two ways, phagocytosis and autophagy.
Phagocytosis is
engulfing solid particles and breaking them down.
Autophagy is
recycling the cell’s own organic material (self-eating).
The vacuoles is the
handyman. It performs a variety of functions like food vacuoles (formed by phagocytosis), digestion, and storage.
Where is the central vacuole found?
found in plants. It stores inorganic ions, allows cells to grow large without increasing cytoplasm, and help plant remain rigid.
Peroxisomes are
the detoxifer. It is the center for redox reactions that often produce H2O2 (toxic) and also contain catalase which breaks down H2O2. Also breakdown fatty acids and detoxifies alcohol and other toxic compounds.
Mitochondria is the powerhouse of the cell, why?
it is the site of cellular respiration (produces energy for the cell in the form of ATP), it also contains their own DNA and ribosomes. It has a double membrane and is found in almost all eukaryotic cells.
Chloroplasts are
the sugar factory. They have a double membrane, contain their own DNA and ribosomes, contain chlorophyll, and are the site for photosynthesis.
How does transport within the cell?
Nuclear transport is highly regulated. Proteins are destined for the nucleus have specific amino acid sequence (zip code). Nuclear localization sequence = molecular zip code. Nuclear export sequence.
What helps nuclear import and export?
importin and exportin.
How do proteins get to their specific locations?
all proteins synthesis starts on free ribosomes. Proteins meant for endomembrane system or secretion are marked by a signal peptide (amino acids, ER signal sequence). Signal-recognition particle (SRP) escorts the ribosome to the ER membrane.
