Chapter 3 Cells, Organelles & Tissues Flashcards
What is a cell?
The cell is the smallest structural and functional unit capable of carrying out life processes
The primary units of life
What does a cell’s function depend on?
It depends on it’s unique complement of proteins
What does an organism’s structure and function depend on?
It depends on the individual and collective structural characteristics and functional capabilities of its cells.
What are the characteristics of a cell?
Highly organized and compartmentalized
There are many types of cells in the body and each one are specialized for a specific function.
What are the three main parts of a cell?
Plasma membrane
Cytoplasm
Organelles
What creates compartments within a cell?
Cell membranes create compartments
A phospholipid bilayer and its associated proteins make up what membranes?
The plasma membrane
Membrane around the nuclear envelope
The membranous organelles
What are the properties that a cell exhibits due to membrane?
Selectively permeability
The membrane contains proteins that allow molecules to cross the membrane
How does the cell membrane allow molecules to cross the plasma membrane
Via transporters (carriers) By channels
What might some cells have that will allow the cell or organelles to interact with the environment?
Some cells have receptors for:
Cell recognition
Surface Markers
And receptors with various functions
What is contained on or within the plasma membrane of a cell and characteristics or properties does this give the cell?
The membrane is a lipid bilayer containing integral proteins, cholesterol and glycosylated lipids
These properties along with the plasma membrane make the cell DYNAMIC & FLUID!
Which direction does the phospholipid heads face?
The face the aqueous intracellular and extracellular compartments
Where do the lipid tails of the plasma membrane face? What can insert between the lipid layer?
They form the interior layer of the membrane
Cholesterol molecules insert themselves in the lipid layer
What crosses the entire plasma membrane?
What is used to anchor the plasma membrane and to what are they anchored to?
Lipid anchor proteins anchor the membrane to cytoskeleton proteins
What are the two most common processes that move large molecules and particles from the extracellular environment to the inter of the cell?
Phagocytosis “cell eating”
Endocytosis, and exocytosis
Some cells exhibit many folds and invaginations on some cells surfaces, what are they called and what is their function and give an example of a cell.
Microvilli
Increases surface area
Optimize diffusion / absorption
Columnar cells of the intestine
What is the region that is bound by the plasma membrane, and what is its consistency like?
The cytoplasm is the region bound by the plasma membrane
Considered a jelly-like matrix with a cell
What is within the cytoplasm that gives the cell its structure?
What is its function?
The cytoskeleton gives the cell a scaffold-like structure, which provides shape to the cell.
It helps with transportation of organelles in the cell
What is the components of the cytoskeleton?
Microfilaments
Microtubules
Intermediate filaments
What is the largest cytoskeleton fiber?
Microtubules
What supports the microvilli and forms a network just inside the cell membrane
Microfilaments for a network just inside the cell membrane and support the microvilli
Which organelles are membrane bound?
Golgi
ER
Mitochondria
Lysosomes, peroxisomes
Which organelles are non-membrane bound within a cell?
Ribosomes
Centrioles
What is contained with the nucleus describe the nucleus!
The genetic blueprint is contained within the nucleus
-Chromosomes are found with the nucleus
The nucleus is enclosed by a double-membrane nuclear envelope that has nuclear pores that allow for communication with the cytoplasm
What encodes all of our traits and where are they found?
First thing is Chromosomes are found within the nucleus and genes, which encode all traits are found on the chromosomes.
When are genes typically expressed?
Genes are typically expressed during appropriate times and in response to specific signals
What else does the nucleus contain?
It contains 1 to 4 larger dark-standing bodies of DNA, RNA, and proteins called nucleoli.
What connect to the outer membrane of the nucleus?
The endoplasmic reticulum connects to the outer membrane of the nucleus
What is the estimated total number of base pairs in human DNA and how does it correlate to our genes?
Estimated 3 billion base pairs but only a small percentage of DNA encodes a gene.
A gene can be made up of several thousand base pairs
What is the beginning of gene transcription?
What is removed and what remains of the RNA transcript?
RNA polymerase unzips the DNA strand and synthesizes an initial transcript.
During this process, the introns are excised out and the exons remain to give mRNA
-mRNA is translated by what? What is the complement to mRNA and what is its job?
-mRNA is translated into proteins by free or bound ribosomes. Free ribosomes takes place in the cytoplasm, and bound ribosomes are bound to the rough ER.
Transfer RNA contains a complementary triplet code (or anticodon) that binds the codon
What is the job of tRNA?
-tRNA has a single amino acid with a complementary triplet that will bind with its complement of mRNA. This is how amino acids are placed in a chain called a polypeptide.
As the ribosome moves down the mRNA, the amino acids are linked together.
Which direction is RNA and DNA read? Primarily mRNA during transcription and translation?
It’s read 5’ to 3’
What is the most common start and stop codons and what amino acid do they code for?
AUG (Methionine) most common start codon
UAA - stop
UAG - stop
UGA - stop
How many codons in the genetic code not including the stop codons?
61 code
3 codes that are stop codons
What is the purpose of mitotic cell division?
In adults it is necessary for replacing worn or dying cells.
What are the two distinct phases of mitotic cell division?
Interphase
The mitotic phase where division takes place
Define and break down Interphase
- cell is not dividing
- G1 cell performs normal physiological roles (centrioles replicate
- S where DNA is replicated
- G2 cell is ready to enter the mitotic phase and divide
What are all of the phase of the mitotic division?
Interphase Prophase Metaphase Anaphase Telophase/ cytokinesis
What takes place during Prophase?
Chromosomes appear as sister chromatids at the centromere. The nuclear membrane dissociating, centromeres move to the poles
Spindle fibers form from the centrosomes
Nucleolus is no longer visible
What takes place during Metaphase?
Chromosomes align at the equator of the cell. The nuclear membrane completely disappears.
The spindle fibers from each centrosomes attaches to the centromere
What takes place during Anaphase?
Centromeres split as spindle fiber pull chromatids to opposite poles
What takes place during Telophase and cytokinesis?
Cytoplasm divides between daughter cells. Spindle fibers dissociate. Chromosomes decondense as a new nuclear membrane forms
The chromosomes become longer, thinner, and less distinct
New nuclear membrane forms
The nucleolus reappears
Cell division is nearly complete
–Furrowing of the cell begins and the cell divides forming two identical daughter cells
What is the term for cellular division in germ cells?
Where does this process occur and what does it yield?
Meiosis is the division of germ cells
This process occurs in the gonads that yield haploid gametes
How many stages are there in Meiosis?
What does Meiosis yield?
Meiosis I and Meiosis II
1 diploid (2n) parent cell yields 4 daughter cells, all haploid (1n)
In meiosis DNA is replicated and divided how many times?
DNA is replicated (only) once and divided twice
What two processes gives the most genetic variability during meiosis?
Random assortment
Crossing over
During Meiosis I, what is the distinct process that takes place that gives genetic variability?
During Prophase 1, tetrads form, as the homologous chromosome line up next to each other. Crossing-over between non-sister chromatids takes place.
During Anaphase 1 what specifically takes place between the chromosomes?
Spindle fibers separate the homologous chromosomes from each other
***Thus the maternally derived chromosomes separates from the paternally derived chromosome
During Meiosis II is there interphase, if so explain the process?
There is a brief interphase that follows the first meiotic division, during this time NO replication occurs
