WK 3 Lecture Study Guide: Cells & Cell Functions Flashcards
Know the major functions of the following cellular organelles:
A. Nucleus—also know the structure (nuclear membrane, nuclear pores)
- Surrounded by a membrane called the nuclear envelope. This membranous covering consists of two adjacent lipid bilayers with a thin fluid space in between them.
-Spanning these two bilayers are nuclear pores. A nuclear pore is a tiny passageway for the passage of proteins, RNA, and solutes between the nucleus and the cytoplasm.
-Proteins called pore complexes lining the nuclear pores regulate the passage of materials into and out of the nucleus.
Inside the nuclear envelope is a gel-like nucleoplasm with solutes that include the building blocks of nucleic acids.
-There also can be a dark-staining mass often visible under a simple light microscope, called a nucleolus (plural = nucleoli).
-The nucleolus is a region of the nucleus that is responsible for manufacturing the RNA necessary for construction of ribosomes. Once synthesized, newly made ribosomal subunits exit the cell’s nucleus through the nuclear pores.
B. Cell Membrane—also know the structure (bilayer of phospholipids, proteins present)
C. Golgi Apparatus-responsible for sorting, modifying, and shipping off the products that come from the rough ER, much like a post-office.
D. Ribosomes–A ribosome is an organelle that serves as the site of protein synthesis. It is composed of two ribosomal RNA subunits that wrap around mRNA to start the process of translation, followed by protein synthesis.
E. Smooth ER:
-main functions of the smooth ER is in the synthesis of lipids.
-The smooth ER synthesizes phospholipids, the main component of biological membranes, as well as steroid hormones.
-the smooth ER also sequesters (i.e., stores) and regulates the concentration of cellular Ca++, a function extremely important in cells of the nervous system where Ca++ is the trigger for neurotransmitter release. -The smooth ER additionally metabolizes some carbohydrates and performs a detoxification role, breaking down certain toxins.
Rough ER (RER)
F. Rough Endoplasmic-is so-called because its membrane is dotted with embedded granules—organelles called ribosomes, giving the RER a bumpy appearance.
-the primary job of the rough ER is the synthesis and modification of proteins destined for the cell membrane or for export from the cell.
-For this protein synthesis, many ribosomes attach to the ER (giving it the studded appearance of rough ER). Typically, a protein is synthesized within the ribosome and released inside the channel of the rough ER, where sugars can be added to it (by a process called glycosylation) before it is transported within a vesicle to the next stage in the packaging and shipping process: the Golgi apparatus.
G. Mitochondria-the “energy transformer” of the cell.
H. Lysosomes-is an organelle that contains enzymes that break down and digest unneeded cellular components, such as a damaged organelle. (A lysosome is similar to a wrecking crew that takes down old and unsound buildings in a neighborhood.)
Name the stages of mitosis and what is happening (in general) in the cell during those stages.
I
Preach
Mercy
And
Truth
1)Interphase:
-Prepares for cellular division
-Cell performs all normal functions
-Represents cell growth and DNA replication prior to prophase.
2)Prophase:
-Distinct pairs of chromosomes apparent
Centrioles migrate to opposite ends of the cell, forming spindle fibers
-Chromatids held together by centromeres
-Nucleolus and nuclear membrane disappear
3)Metaphase:
-Chromosomes line up on metaphase plate
-Centromere attaches to spindle fiber
4)Anaphase:
-Centromeres separate
Individual chromosomes move to ends of cell.
-Cytokinesis begins
5)Telophase:
-Chromosome migration complete
-Nuclear envelopes develop around chromosomes
-Nucleoli develop
-Spindle fibers disappear
-Cleavage furrow near complete
What is cytokinesis?
-True division of the cell(divides the cytoplasm into two distinctive cells.)
-Begins during anaphase
-Completed at the end of telophase
What is osmosis?
is the diffusion of water through a semipermeable membrane.
Describe the process of DNA replication.
Each cell in your body (with the exception of germ cells) contains the complete set of your DNA. When a cell divides, the DNA must be duplicated so that the each new cell receives a full complement of DNA.
What is transcription?
-Occurs in the nucleus
-Involves copying information from a DNA molecule and putting it in the form of messenger RNA
-DNA unwinds and hydrogen bonds broken
-Only one template used to make mRNA strand
What is translation?
-Process of translating the mRNA code into a protein
-Occurs in the cytoplasm
-ribosomes or on rough endoplasmic reticulum
-tRNA brings amino acid for each codon to the ribosome
-mRNA molecule is read until stop codon is reached
What is a triplet (codon)? What is its significance in protein synthesis?
A codon is a three-base sequence of mRNA, so-called because they directly encode amino acids. Like DNA replication, there are three stages to transcription: initiation, elongation, and termination.
what are the steps in protein synthesis?
Translation and Transcription
Types of RNA
-Messenger RNA (mRNA)
Carries code for the protein to be synthesized from the nucleus to the ribosome
-Transfer RNA (tRNA)
Carries amino acid to the ribosome to be incorporated into the synthesized protein
What is the cell membrane?
Also called plasma membrane or plasmalemma
Outer boundary of the cell
4 Major Celular Structures?
1)Cell Membrane
-Outer boundary of cell
2)Cytoplasm
-Substance that holds
organelles
3)Organelles
-Perform specific cellular functions
4) Nucleus
-Control center of the cell
What is the cell membrane?
Also called plasma membrane or plasmalemma
Outer boundary of the cell
Cell membrane functions?
-Physical Isolation
-Regulation of exchanges
with the environment
-Sensitivity
-Structural support
Cell membrane lipids?
-Phospholipids form two distinct layers
-Surface lipids of membrane are hydrophilic and will allow water to enter into the surface of the membrane
-Internal lipid portion of membrane is hydrophobic and will not allow water and other solutes into the cell
Isolates cytoplasm from the surrounding environment
