Chapter 4 quiz Flashcards
What is cell fractionation? What is the purpose of it
A process that breaks up the cells and separates he components using centrifugation. This enables scientists to determine the functions of organelles
What are the characteristics of prokaryotic cells?
- No nucleus
- DNA in an unbound region called the nucleoid
- No membrane-bound organelles
- Cytoplasm bound by plasma membrane
What are the basic features of all cells?
- Plasma membrane
- Semifluid substance called cytosol
- Chromosomes
- Ribosomes
What is the plasma membrane?
A selective barrier in a cell that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell, made up of a phospholipid bilayer
What are the characteristics of Eukaryotic cells?
- DNA in the nucleus that is bounded by a membranous nuclear envolope
- Membrane-bound organelles
- Cytoplasm in the region between the plasma membrane and nucleus
- Generally larger the prokaryotic cells
What is the nucleus and what surrounds it?
The nucleus contains most of the cells genes and is usually the most conspicuous organelle. It is surrounded by the nuclear envelope, which is made up of 2 nuclear membranes that are lipid bilayers
What are ribosomes?
Ribosomes use information in the DNA to make proteins. The are complexes of ribosomal DNA, and ribosomes are proteins themselves
What is the nuclear lamina?
The structure that maintains the shape of the nucleus, it is composed of protein and adds support
Where do ribosomes carry out protein synthesis? What are these different type of ribosomes called?
- In the cytosol(free ribosomes)
2. On the outside of the endoplasmic reticulum or nuclear envelope(bound ribosomes)
What are chromosomes and what makes them up?
Chromosomes are he discrete units that DNA is organized into in the nucleus. Chromosomes are made up of DNA and proteins called chromatin
When and how does chromatin condense?
Chromatin condenses to form discrete chromosomes as a cell prepares to divide. The DNA wraps around the like a spool
What is the nucleolus?
The site of ribosomal RNA(rRNA) synthesis inside the nucleus
What is the endoplasmic reticulum and its characteristics?
The ER membrane is continuous with the nuclear envelope. It is made up of the smooth ER(lacks ribosomes) and rough ER(surface is studded with ribosomes). It takes up a lot of the cell and acts as a biosynthetic factory
What is the purpose of the endomembrane system?
To regulate protein traffic and perform metabolic functions in the cell
What are the 2 ways the endomembrane system stays connected?
- Continuous: No vesicles
2. Connected by vesicles
Why is the ER folded?
To save space and be efficient
What are vacoules?
Large vesicles
What makes up vesicles?
Lipid bilayers
What is the golgi apparatus?
An organelle that:
- Manufactures certain macromolecules
- Modifies products of ER
- Sorts packages materials into transport vesicles
The golgi apparatus consists of flattened sacs called cisternae
What is the function of the rough ER
- Secrete glycoproteins from bound ribosomes
- Distribute transport vesicles
- Membrane factory for cell
What is the cis and trans face of the golgi apparatus?
Cis: receiving side
Trans: Shipping side
What is a lysosome?
A membranous sac of hydrolic enzymes that digest macromolecules. Lysosomal enzymes also hydrolyze proteins, fats, polysaccharides and nucleic acids.
In what conditions do lysosomal enzymes work best?
An acidic environment, with a pH of 4.5-5
What is phagocytosis? What kinds of cells conduct phagocytosis?
When a cell engulfs another cell or large particle. This happens when he lysosome fuses with a food vacuole and digests the molecules. It is carried out by some protists and immune cells of animals
What is autophagy?
A cellular process where lysosomes use their hydrolytic enzymes to recycle the cell’s own organic material. A damaged organelle or small amount of cytosol becomes surrounded by a double membrane and is broken down by the lysosome, then small parts are released to the cytosol for reuse
How does a lysosome digest stuff?
It bonds to a food vesicle and breaks down what’s in it
How are food vacuoles formed and what are the types of food vacuoles?
Food vacuoles are formed through phagocytosis. Contractioe vacuoles pump excess water out of cells and central vacuoles hold organic compounds and water
Where do ribosomes synthesize proteins?
Rough ER and nuclear envelope
What are mitochondria?
The sites of cellular respiration in a cell
What are chloroplasts?
The sites of photosynthesis in plant cells
What is the endosymbiont theory? Where do we believe mitochondria and chloroplasts originated? What evidence supports this theory?
The endosymbiont theory states that an ancestor if eukaryotic cells engulfed an oxygen-using non-photosynthetic prokaryotic cell. These cells merged to become a cell with a mitochondria. A similar scenario with photosynthetic cells could have also resulted in chloroplasts. The fact that mitochondria and chloroplasts have 2 membranes and not 1 like most of the endomembrane system, they contain ribosomes and DNA, and they are somewhat independent supports this theory.
What is the structure of the mitochondria membranes?
They have a smooth outer membrane and an inner membrane that is folded to save space. The inner membrane creates two compartments, the intermembrane space and mitochondrial matrix
What is included in the structure of a chloroplast?
- Thylakoids: membranous sacs, stacked to form a granum
2. Stroma: the internal fluid
What group of plant organelles is the chloroplast apart of?
Plastids
What are peroxisomes?
An organelle bounded by a single membrane, that produces hydrogen peroxide by transferring H2 to O2 using enzymes
What is the cytoskeleton?
A network of fibers that organizes structures and activities in a cell along with structural support
What is motility and how is it achieved?
The ability of a cell to move. The cytoskeleton interacts with motor proteins to achieve this
What are the 3 main types of fibers that makes up the cytoskeleton?
- Microtubules: Thickest fibre
- Microfilaments: also called actin filaements, the thinnest components
- Intermediate filaments: medium in thickness
What are the main functions of micotubules?
- Maintain cell shape
- Cell motility
- Chromosome and organelle movements
What are the main functions of microfilaments?
- Maintain cell shape
- Changes in cell shape
- Cell motility
- Division in animal cells
- Cytoplasmic streaming in plants
What is the structure of microtubules?
They are hollow rods constructed from glubular protein dimers called tubulin(2 monomers)
What are centrioles, centrosomes and their structure?
Microtubules grow out from a centrosome near the nucleus. The centrosome has a pair of centrioles in a T shape, along with nine triplets of microtubules arranged in a ring
What are cilia and flagella and what controls them?
Cilia and flagella are microtubule-containing extensions projecting from some cells
What is the structure if cilia and flagella? What makes them move?
A basal body anchors them, and a motor protein drives the bending movements of them. A core of microtubules is sheathed by the plasma membrane
What is myosin?
Microfilaments that function in cellular motility interact with the motor protein myosin
Which cells have cell walls? what is the cell wall made of?
Plant cells, prokaryotes, fungi and some protists have cell walls. They are made up of cellulose fibers embedded in other polysaccharides and protein
What are the layers of cell walls?
- Primary cell wall: relatively thin and flexible
- Middle lamina: Thin layer between primary walls of adjacent cells
- Secondary cell wall: In some cells, added between plasma membrane and cell wall
What is the plasmodesmata?
Channels between adjacent plant cells
What is the extracellular matrix?
The covering of animal cells in place of a cell wall. It binds to receptor proteins in the plasma membrane
What are integrins?
Receptor proteins with two subunits that span the plasma membrane that bind their cytoplasmic side to associated proteins attached to microfilaments and bind to the extracellular matrix on the other side. This transmits signals from the exterior to the interior of the cell so it can adapt
What are the three types of cell junctions in animal cells?
- Tight junctions: prevent fluid from moving across a layer of cells
- Desmosomes
- Gap junctions
Which organelles are apart of the endomembrane system?
ER, Golgi apparatus, Lysosome, Vacuole
