AP Biology Chapter 6
How does the structure of the cytoskeleton contribute to its function?
A cytoskeleton is a network of fibers extending throughout the cytoplasm. The function of cytoskeleton is organizing the structures and activities of a cell. It is composed of microtubules, microfilaments, and intermediate filaments. It gives mechanical support to the cell and maintains its shape. The network of structural proteins that extend throughout the cytoplasm, structural proteins, give cell structural support and anchor organelles. The network of fibers also helps organelles and chromosomes to move around in the cell (transport like a monorail).
Function of a lysosome
A lysosome has three main functions: the breakdown/digestion of macromolecules (carbohydrates, lipids, proteins, and nucleic acids), cell membrane repairs, and responses against foreign substances such as bacteria, viruses and other antigens. When food is eaten or absorbed by the cell, the lysosome releases its enzymes to break down complex molecules including sugars and proteins into usable energy needed by the cell to survive. If no food is provided, the lysosome's enzymes digest other organelles within the cell in order to obtain the necessary nutrients.
How is the structure of a lysosome related to its function?
A lysosome is a membranous sac of hydrolytic enzymes that an animal cell uses to digest macromolecules. The membranous sac helps the lysosome to fuse with other vesicles to get their macromolecules from food or broken organelles, digestive enzymes help to break those down to monomers that can be reused as nutrients. The membranous sac also is able to engulf substances to aid in digestion. Enzymes are contained by a membrane because they are hydrolytic and would destroy the rest of the cell if released out of the membrane.
Mitochondrion
A mitochondrion is an organelle where cellular respiration occurs and most ATP is generated. It is found in all eukaryotes and has two membranes (inner and outer). Some cells have a singular large mitochondria but more often a cell has hundred or even thousands of mitochondria.
Why will it make me cringe if you ever say that cells "make" energy?
Cells do not "make" energy, they convert energy into useable forms. Cellular respiration is used to make ATP, adenosine triphosphate, which provides the energy that the cells need to be able to carry out their functions in living cells. All cells carry out some form of cellular respiration, either aerobic or anaerobic. The cells that perform aerobic respiration need oxygen to carry out the process, while cells that use the anaerobic process do not, instead relying on fermentation. Plants use photosynthesis. This process uses sunlight processed through the chlorophyll of the plants to create the sugars needed for energy. Without this process the plants could not absorb carbon dioxide or produce oxygen that other living organisms need to live.
Explain cytoplasmic streaming related to vacuoles
Cytoplasmic streaming is the directed flow of cytosol (the liquid component of the cytoplasm) and organelles around large fungal and plant cells through the mediation of actin. This movement aids in the delivery of organelles, nutrients, metabolites, genetic information, and other materials to all parts of the cell. Cytoplasmic streaming occurs in the cytoskeleton of the cell, causing the cytosol to move as well.
Rough ER
Functions of Rough Endoplasmic Reticulum include: Making secretory proteins Manufacturing membranes
Smooth ER
Functions of Smooth Endoplasmic Reticulum include: synthesis of lipids (ex. Sex hormones and steroids) metabolism of carbohydrates detoxification of drugs and poisons
How does the structure of a golgi complex help it accomplish its goals?
It is especially extensive in cells specialized for secretion. Its consists of flattened membranous sacs. These sacs are not physically connected. These sacs allow for the transport of vesicles from the ER. The ER can add its membrane and the contents of its lumen to the cis face by fusing with a golgi membrane. Then the trans face of a golgi membrane will pinch it off and allow it to travel to other sites. Products of the ER are usually modified during their transit from the cis face to the trans face. Having lots of membrane surface area allows for more transport.
stroma
It is the fluid outside of the thylakoid that contains the DNA of chloroplasts and ribosomes and many enzymes. It is the innermost matrix of chloroplasts and its fluid is dense and helps with support.
Explain one normal function of lysosomes in multicellular organism and one abnormal function?
Lysosomes also use their hydrolytic enzymes to destroy pathogens (disease-causing organisms) that might enter the cell. Macrophages (a type of white blood cell) carry out phagocytosis. Macrophages helps defend the body by engulfing pathogens, fusing with lysosomes, which then destroying bacteria and other invaders. Some people have inherited lysosomal storage diseases. These people lack a functioning hydrolytic enzyme that is usually in a lysosome. Lysosomes then can not break down substances and then they become engorged with these substances. They begin to interfere with cellular activities. One example is Tay-Sachs disease.
What is the advantage of having membrane bound organelles?
Membrane bound organelles help to compartmentalize the cell so that each reaction in the organelle is separate from those of other organelles. Since several organelles can carry out different functions simultaneously, keeping organelles separate can increase efficiency. Membranes also offer protection, they can keep things inside or outside of the organelle. Also, organelles can be close to other organelles that have related functions. For example, organelles producing proteins can be near other organelles involved in transporting those proteins.
How do prokaryotes function without membrane bound organelles?
Prokaryotic cells carry out cellular respiration within the cytoplasm or on the inner surfaces of the cells. The prokaryotic cell membrane performs the function of the eukaryotic inner mitochondrial membrane, and the prokaryotic cytoplasm performs the function of the eukaryotic mitochondrial matrix.
Describe the structure and the function of a ribosome
Ribosomes are complexes made of ribosomal RNA and protein. They carry out protein synthesis. There are two types of ribosomes: Free Ribosomes which are ribosomes suspended in the cytosol, and Bound Ribosomes which are attached to the outside of the endoplasmic reticulum or nuclear envelope. Free ribosomes produce proteins for the cell, while bound ribosomes produce proteins that are transported out of the cell.
Role of a Golgi Complex
The Golgi complex in a cell is the center for manufacturing, warehousing, sorting and shipping of proteins.
where is chlorophyll found
The chlorophyll molecules sit inside each thylakoid membrane and capture light from the sun. The stroma and the stacks of thylakoid membranes are found inside of the inner membrane.
outer membrane of chloroplasts
The contents of a chloroplast are partitioned from the cytosol by an envelope consisting of two membranes. The outer membrane is permeable to small organic molecules allowing for transport into and out of the cell.
Differences between smooth and rough ER
The difference between rough and smooth endoplasmic reticulum is that the rough endoplasmic reticulum has ribosomes attached to the outer surface of the membrane and the smooth endoplasmic reticulum does not have attached ribosomes.
Endoplasmic Reticulum (ER)
The endoplasmic reticulum is an extensive network of membranous tubules and sacs that serve a variety of functions in plant and animal cells. Functions of Endoplasmic Reticulum include: Synthesis of lipids Metabolism of carbohydrates Detoxification of drugs and poisons Making secretory proteins Manufacturing membranes
Explain Turgor pressure related to vacuoles
Turgor pressure exerted by the vacuole is essential in supporting plants in an upright position. This pressure, turgidity, is caused by the osmotic flow of water from an area of low solute concentration outside the cell into the cell's vacuole, which has a higher solute concentration. Healthy plant cells are turgid and plants rely on turgidity to maintain rigidity. This turgor pressure is not observed in animal cells because they have no cell walls. Cell walls prevent plant cells from being burst by the flow of water into the cell -- animal cells do not have a cell wall. Animal cells must either continually pump out water, with a contractile vacuole, or live in an isotonic solution where there is no osmotic pressure.
Explain the functions of vacuoles and explain how they differ between plant cells and animal cells
Vacuoles are membrane-bounded vesicles whose functions vary in different kinds of cells. Food vacuoles, formed by phagocytosis, are present in animal cells. Contractile vacuoles, that pump excess water out of the cell are present in many freshwater protists. Plant cells have a large central water vacuole and animal cells only have many small vacuoles. The central vacuole is a large fluid-filled organelle that stores water, enzymes, metabolic wastes, and other material. It is formed by other vacuoles that fuse together. It can make up to 90 percent of the plant's volume and can push all of the other organelles into a thin layer against the cell membrane.
thylakoids
a flattened membranous system of interconnected sacs that can be stacked like poker chips. They are the site of the light-dependent reactions of photosynthesis. The chlorophyll molecules sit inside each thylakoid membrane and capture light from the sun.
inner membrane of mitochondria
divides the mitochondrion into two internal compartments (the intermembrane space and the mitochondrial matrix. A highly folded membrane gives a large surface area, enhancing productivity for cellular respiration.
matrix
fluid-filled space surrounded by the inner membrane of the mitochondrion. It contains many different enzymes including the mitochondrial DNA and ribosomes. Enzymes in the matrix catalyze some steps of cellular respiration.
chloroplast
is a specialized member of a family of closely related plant organelles called plastids. They contain chlorophyll, along with enzymes and other molecules that function in photosynthesis. Chloroplasts are found in leaves and other green organs of plants and algae.
inner membrane of chloroplasts
is less permeable and studded with transport proteins. This is the inner membrane of the envelope.
outer membrane of mitochondria
is smooth and it is the gateway to the mitochondrion, just like the cell membrane is for the cell. It has porins to allow smaller proteins in and protein complexes to allow bigger proteins in. It works in concert with the inner membrane to allow these proteins into the matrix.
inter membrane space of mitochondria
is the area between the inner and outer membranes. It has an important role in the primary function of mitochondria, which is oxidative phosphorylation.
cristae
is the inner folds of the mitochondrion where most ATP is made.
granna
stacks of thylakoids. Light-dependent reactions of photosynthesis takes place here.