Chapter 1: Cellular Biology Flashcards
Prokaryotes include:
Cyanobacteria (blue-green algae), bacteria, and rickettsia
Where does the word eukaryote come from?
Eu = good Karyon = nucleus
What defines a eukaryote?
a characteristic set of membrane-bound intracellular compartments called organelles that includes a well-defined nucleus
What defines a prokaryote?
Contain no organelles, and their nuclear material is not encased by a nuclear membrane. They also lack a distinct nucleus.
Describe the nuclei of prokaryotic cells.
Genetic information is stored in a single circular chromosome and lack histones
Eukaryotes include:
Humans, animals, plants, single celled-organisms such as fungi, protozoa, and most algae
p. 2
Describe the basics of cell differentiation
Some cells eventually perform one kind of function and others perform other functions
Name the eight chief cellular functions
Communication Conductivity Excretion Metabolic absorption Movement Reproduction Respiration Secretion
What are the 3 components of a “typical” eukaryotic cell? (p. 2)
outer membrane called the plasma membrane or plasmalemma, a fluid filling called cytoplasm, and the intracellular organelles.
Describe the membranes surrounding the nucleus.
Two membranes comprise the nuclear envelope. The outer membrane is continuous with membranes of the endoplasmic reticulum. The inner membrane encloses the neoplasm.
What is the nucleus? What is contained in the nucleolus?
The largest of the organelles; it contains the nucleolus. The nucleolus is a small dense structure composed largely of RNA. It contains most of the cellular DNA and the DNA-binding proteins (histones).
What do histones do?
Why is this important?
Bind to DNA to cause it to fold into chromosomes.
Wrapping of DNA into tight packages of chromosomes is essential for cell division in eukaryotes.
What is the primary function of the nucleus?
Cell division and control of genetic information.
Where does most of the processing of RNA occur?
in the nucleolus (p. 4)
What is the cytoplasm and the cytoplasmic matrix?
Cytoplasm is an aqueous solution (cytosol) that fills the cytoplasmic matrix, which is the space between the nuclear envelope and the plasma membrane.
What fraction of the cell’s volume is represented by the cytosol?
about 1/2
What is contained in the cytosol?
- thousands of enzymes involved in intermediate metabolism
- ribosomes which make proteins
- storage for fat, carbohydrates, and secretory vesicles
Where do newly synthesized proteins remain if they lack a signal for transport to a particular organelle?
In the cytosol
Where are ribosomes synthesized and how do they get to the cytoplasm?
in the nucleolus; they are secreted into the cytoplasm through pores in the nuclear envelope called nuclear pore complexes (NPCs).
What are ribosomes?
RNA-protein complexes (also called nucleoproteins) which synthesize proteins.
What is the endoplasmic reticulum?
a membrane factory that synthesizes and transports the protein and lipid components of most of the cell’s organelles.
What does the endoplasmic reticulum consist of?
a network of tubular or saclike channels called cisternae, that extend throughout the cytoplasm and are continuous with the outer nuclear membrane
What are the two types of folded membranes within the endoplasmic reticulum?
rough (granular) or smooth (agranular).
Why is the rough endoplasmic reticulum rough? (p. 6)
because ribosomes and ribonucleoprotein particles are attached to it
What is the function of the Golgi complex?
Proteins from the ER are processed and packaged into small membrane-bound sacs called secretory vesicles, which collect at the end of the membranous folds of the Golgi bodies – called cisternae.
Lysosomes function as…
the intracellular digestive system.
p. 7
Lysosomal enzymes are capable of…
digesting most cellular constituents completely to their basic components
What do lysosomes contain?
More than 40 digestive enzymes called hydrolases which catalyze bonds in proteins, lipids, nucleic acids, and carbohydrates.
Why is the integrity of the lysosomal membrane so important? (p. 7)
It acts as a shield between the powerful digestive enzymes in the lysosome and the cytoplasm. Disruption of this membrane by various treatments or cellular injury leads to release of enzymes which can cause cellular self-digestion.
Lysosomal storage diseases may be the result of… (p. 7)
…a genetic defect or lack of one or more lysosomal enzymes.
An example of a lysosomal storage disease is Pompe disease. What causes this?
the lack of lysosomal alpha-1,4-glucosidase leads to an accumulation of glycogen in lysosomes. It is also called acid maltase deficiency.
Describe the role of lysosomes in gout. (p. 7)
undigested uric acid accumulates within lysosomes, damaging the lysosomal membrane. Enzyme leakage occurs, resulting in cell death and tissue injury.
What is the difference between a primary lysosome and a secondary lysosome (aka: heterophagosome)? (p. 8)
A primary lysosome does not maintain such an acidic internal pH. They are inactive in a sense. When a primary lysosome fuses with a vacuole or other organelle, its pH falls and the hydrolytic enzymes become activated.
What is the term for degradation process of intracellular debris and what does this involve? (p. 8)
Autophagy. This process promotes homeostasis and involves continuous biosynthesis and cell turnover.
Products of autophagy pass out of the lysosome and are ______ by the cell. Indigestible material is stored in vesicles known as ________ ______. The contents are ________ ________ from the cell.
reused
residual bodies
actively expelled
(p. 8)
High concentrations of lipids may accumulate within the residual bodies and remain there for a long time. The lipids are eventually oxidized, and a pigmented substance containing polyunsaturated fatty acids and proteins accumulates in the cell. This pigmented substance termed __________, is often called “age pigment” or “age spots”, and is noted in older individuals.
lipofuscin
p. 8
Peroxisomes (microbodies) are membrane-bound organelles that contain several oxidative enzymes such as ________ and _____ _______.
catalase
urate oxidase
(p. 8)
