MolecularBiology Flashcards
T-cell precursors originate in the _____ _____.
bone marrow
The thymus is located in the ____ in the thoracic cavity.
mediastinum
The thymus is a ________ lymphoid organ.
primary
The thymus is most active during _______.
childhood
The thymus secretes chemokines to stimulate ______ precursors to go to the Thymus and undergo a maturation process.
T-cells
The thymus secretes chemo-tactic agents such as:
Thymosine
Thymotaxin
Thymopoietin
Thymic factors
The spleen and the lymph nodes are _____ lymphoid organs.
secondary
The thymus secretes chemokines that stimulate a T-cell precursor to produce _____ “recombinases” that shuffle DNA to produce specific shape TCRs.
enzyme
T-cells produce enzyme “recombinases” called _____ and _____ that shuffle DNA to produce specific shape TCRs.
RAG1, RAG2
Thymic chemokines stimulate a T-cell precursor to express TCRs as well as _____ and _____ surface glycoproteins.
CD4, CD8
Positive selection of T-cell precursors in the Thymus is the process of thymic cell MHC-I and MHC-II binding to _____ and ____, respectively.
CD8, CD4
CD8 and CD4 stands for
Cluster of Differentiation
a glycoprotein on the surface of immune cells including:
T-cells
Monocytes
Macrophages
Dendritic cells
Cluster of Differentiation (CD8 or CD4) are
glycoproteins on the surface of immune cells including:
T-cells
Monocytes
Macrophages
Dendritic cells
Cluster of Differentiation (CD8 or CD4) are surface glycoproteins found on ____
immune cells including:
T-cells
Monocytes
Macrophages
Dendritic cells
After undergoing positive selection, T-cell precursors in the Thymus undergo
negative selection.
TCRs do not recognize self-peptides
The process of T-cell precursors in the Thymus not recognizing self-peptide of thymic cells is called
negative selection.
Negative selection of T-cell precursors in the Thymus comes after positive selection where
CD8 and CD4 bind to thymic cell MHC-I and MHC-II, respectively.
After a T-cell precursor undergoes positive and negative selection in the Thymus, the T-cell upregulates either ___ or ___ to become ___ or ____, respectively.
CD8 or CD4
T-cytotoxic or T-helper
T-helper and T-cytotoxic cells can become
T-regulatory cells, aka Suppressor
Mature T-helper and T-cytotoxic cells travel to secondary lymphoid organs such as the ___ and ____ ____ or stay in the Thymus at Hassal’s corpuscles.
spleen, lymph nodes
Mature T-helper and T-cytotoxic cells may stay in the Thymus at Hassal’s corpuscles or travel to lymph nodes or go to the spleen and become “____ ____.”
white pulp
DNA is converted to RNA via the _______ enzyme.
transcriptase
RNA is converted to DNA via the _____ _____ enzyme.
reverse transcriptase
A mature mRNA does not include ____.
introns
A mature _____ is a complete protein-coding sequence of exons ready for translation into an amino acid chain.
mRNA
Peptides are amino acid chains less than ___.
50
Proteins are amino acid chains greater than ___
50
There are 20 amino acids and __ of them are considered essential.
9
______ are the largest of the white blood cells and are three to four times the size of red blood cells.
Monocytes
______ are the white blood cells that form macrophages and dendritic cells.
Monocytes
They are the largest type of leukocyte and can differentiate into macrophages and myeloid lineage dendritic cells. Half of all monocytes are stored in the spleen in an adult.
A monocyte is part of the _____ immune response.
innate
_____ or a monocyte count higher than 800/µL in adults indicates that the body is fighting an infection.
Monocytosis
Monocytes are produced by the bone marrow from precursors called ____, bipotent cells that differentiated from hematopoietic stem cells.
monoblasts
Bipotent stem cells are capable of differentiating into two cell types.
_____ form part of the main white blood cells in the body alongside neutrophils, basophils, eosinophils and lymphocytes.
Monocytes
_____ progenitor cells can develop into T cells and B cells.
Lymphoid
_____ and their macrophage and dendritic cell progeny serve three main functions in the immune system.
These are phagocytosis, antigen presentation, and cytokine production.
Phagocytosis is the process of uptake of microbes and particles followed by digestion and destruction of this material. Monocytes can perform phagocytosis using intermediary (opsonising) proteins such as antibodies or complement that coat the pathogen, as well as by binding to the microbe directly via pattern-recognition receptors that recognize pathogens. Monocytes are also capable of killing infected host cells via antibody-dependent cell-mediated cytotoxicity. Vacuolization may be present in a cell that has recently phagocytized foreign matter.
Monocytes
T-cell development is regulated by the ______.
Thymus
https://www.youtube.com/watch?v=JeV-HuPq7CI&list=PLpFDoAhR3SQYEeD8XVa0MRSzuhPi0gliH&index=4
The immune system includes ___ layers.
3
barrier, innate, adaptive
https://www.youtube.com/watch?v=k9QAyP3bYmc
______ circulate in the bloodstream for about one to three days and then typically move into tissues throughout the body where they differentiate into macrophages and dendritic cells.
Monocytes
Monocytes are the largest corpuscle in blood. They constitute between 3% to 8% of the leukocytes in the blood.
About half of the body’s monocytes are stored as a reserve in the ____ in clusters in the red pulp’s Cords of Billroth.
spleen
______ a type of eukaryotic cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.
Mitosis
the chromosomes are duplicated during interphase, in preparation for mitosis
____ cells do not undergo mitosis or meiosis.
Prokaryotic
These cells divide by binary fission.
___ cells divide by binary fission.
Prokaryotic
The ___ phase of a cell cycle occurs during interphase, before mitosis (or meiosis), and is responsible for the synthesis or replication of DNA chromosomes. In this way, the genetic material of a cell is doubled before it enters mitosis or meiosis, allowing there to be enough DNA to be split into 2 identical cells.
S
Meiosis is the cell duplication of gametes.
In ___ phase, the cell synthesizes a complete copy of the DNA in its nucleus. It also duplicates a microtubule-organizing structure called the centrosome. The centrosomes help separate DNA during M phase.
S
S phase occurs during interphase. Interphase stages are:
- G1 growth
- S
- G2
S phase is the period of wholesale DNA synthesis during which the cell replicates its genetic content; a normal diploid somatic cell with a 2N complement of DNA at the beginning of S phase acquires a
____ complement of DNA at its end.
4N
The centrosomes help separate DNA during __ phase.
M
Before M phase (Mitosis), during the S phase:
the cell synthesizes a complete copy of the DNA in its nucleus
+
it also duplicates a microtubule-organizing structure called the centrosome.
Mitosis is almost identical in plants except that instead of ______ (cutting off), the cell forms a preliminary structure in the middle that eventually grows into a plant cell wall, thus dividing off the contents into 2 identical sections.
cytokinesis
What are the phases of mitosis?
MATC
Metaphase
Anaphase
Telophase
Cytokineses (after mitosis is over)
https://www.youtube.com/watch?v=1cVZBV9tD-A
What are the phases of a cell?
Interphase (G1, S, G2) and Mitosis (Prophase, Prometaphase, Metaphase, Anaphase, Telophase, Cytokinesis)
The _____ is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis.
nucleolus
Nucleoli also participate in the formation of signal recognition particles and play a role in the cell’s response to stress.
The nucleolus is a dynamic membrane-less structure whose primary function is:
ribosomal RNA (rRNA) synthesis and ribosome biogenesis.
During what phase of Mitosis do the centrosomes begin to separate and the mitotic spindle forms?
During Prophase
Also:
Chromatin condenses into chromosomes
Nuclear envelope is dispersed
What happens during the Prophase of Mitosis?
The centrosomes begin to separate and the mitotic spindle forms.
Also:
Chromatin condenses into chromosomes
Nuclear envelope is dispersed
What happens during the Prometaphase of Mitosis?
2 kinetochores form at each chromosome centromere…
…and microtubules from the centrosomes (at opposite poles of the cell) attach to them
During what phase of mitosis do 2 kinetochores form at each chromosome centromere?
prometaphase
and microtubules from the centrosomes (at opposite poles of the cell) attach to them
What happens during the Metaphase of Mitosis?
All chromosomes align along the metaphase plate.
During what phase of mitosis do the chromosomes align along the metaphase plate?
Metaphase
- Meet
- Middle
The “Meet Middle” happens during what part of Mitosis?
Metaphase
Chromatids are pulled apart toward opposite poles during the _____ of Mitosis
Anaphase
What happens during the Anaphase of Mitosis?
Chromatids are pulled apart toward opposite poles.
What happens during the Telophase of Mitosis?
New nuclear envelopes form.
Chromosomes unfold back into chromatin.
Nucleoli reappear.
Cell continues elongating.
Cytokinesis occurs during the ___ phase of Mitosis.
M
It occurs right after Mitosis.
What happens during the M phase of Mitosis?
Mitosis (PPMAT) and cytokinesis.
What are the respective parts of Mitosis?
PPMAT
Prophase – centrsosomes separate + chromatin condenses + nuclear envelope disperses
Prometaphase – kinetochores + centrosomes
Metaphase – Meet Middle
Anaphase – Apart
Telophase – new nuclear envelopes
