Module 3 Special Topic Flashcards
What is embryogenesis?
Is the process of the embryo forms starting with a single cell
What does embryogenesis achieve?
Patterning- The cells that are forming acquire identity in space and time
The major axis are defined - anterior/posterior and dorsal and ventral. Three germ layers are identified (Gastrulation). Rudiments (undeveloped forms) of the major organs.
Gastrulation generates three germ layers, what are these called?
Ecto (Outside), Meso (Between), Endo (Inside)
At what completed stage of meiosis does the sperm enter the oocyte?
Metaphase Meiosis II
What process happens after fertilisation of the egg (hint: in the fallopian tube)?
Cleavage and formation of the Blastocyst
What special types of formations are formed in the cleavage cell division process?
Morula (latin for raspberry) (3-4 days), and Blastocyst
What are trophoblasts?
Cells that form around and create the outer layer of blastocyst
When does implantation occur?
Usually 6 days after fertilisation
What are the two components of the bilaminar embryonic disc and why are they formed?
Epiblast and Hypoblast, these give the rise to the three types of germ layers (ecto, meso, endo)
What happens to the layers of the embryo in embryonic folding?
Lateral folding- The embryo folds in itself creating a tubular common-like structure making the endoderm the inner layer of what will become the lining of the gastrointestinal tract and the ectoderm now on the outside of the structure which will build the embryo’s outer layers.
Differentiated cells have limited ____
Divisions
What types of cells can replace themselves, and create differentiated daughter cells?
Stem cells
What are the purpose of stem cells?
For growth, renewal and repair
What is meant by ‘decreasing developmental potential’ during embryonic development?
This refers to the process by which cells become more specialized and therefore lose the ability to develop into different types of cells.
For example, a totipotent cell can develop into any cell type, but as it specializes, it becomes pluripotent, then multipotent, and finally unipotent, with each stage having a narrower range of cell types it can become.
What is the stem cell hierarchy?
It is the organisation of stem cells according to their potential to differentiate into different cell types
What is the Totipotent stem cell?
The most potent of the stem cells, it is capable of giving rise to all the cell types of the body and EXTRA embryonic tissues
What is the Pluripotent stem cell?
The second most potent of the stem cells, it is capable of giving rise to all cell types of the body
What is the Multipotent stem cell?
The third most potent of the stem cells, it is only capable of giving rise to cell types of a particular tissue or organ
What is the Nullipotent stem cell?
The least potent stem cell, unable to give rise to other cell types
What type of stem cell is in the skin, allowing for constant renewal?
Unipotent (eg: Differentiating Keratinocytes)
Recap of embryogenesis: How does it all start?
With fertilisation n+n=2n
Recap of embryogenesis: What happens next?
Cleavage and formation of blastocyte
Recap of embryogenesis: What happens after cleavage?
Blastula formation/implantation
Recap of embryogenesis: How do we create three germ layers and what are they?
Gastrulation (endoderm: gut, ectoderm: skin, mesoderm: connective tissues)
Recap of embryogenesis: What happens after Gastrulation?
Organogenesis (Lateral folding)
Recap of embryogenesis: Why do we need stem cells?
To replace differentiated cells, Growth, Repair, Renewal
Recap of embryogenesis: Clinical utility of stem cells?
Long lasting skin grafts (gene edited)
How do amino acids polymerise to form proteins?
Through condensation reactions. The carboxyl group (-COOH) of one amino acid reacts with the amino group (-NH₂) of another. A water molecule is removed (H₂O). A peptide bond (—CO—NH—) is formed. Repeating this creates a polypeptide chain (protein).
What type of bond forms between amino acids in a protein?
A peptide bond.
Formed by a condensation reaction between —COOH and —NH₂ groups.
What is a hydrolysis reaction in proteins?
The reverse of condensation. Breaks peptide bonds. Water is added to split the bond. Turns polypeptides back into amino acids.
What’s the role of water in condensation vs hydrolysis?
Condensation: water is removed to form bonds. Hydrolysis: water is added to break bonds.
Rank these by relative strength (strongest to weakest):
Peptide bond, disulfide bond, hydrogen bond, dipole-dipole interaction, intermolecular forces (Van der Waals)
- Peptide bond (strongest)
→ Covalent bond between amino acids - Disulfide bond
→ Strong covalent bond between sulfur atoms (cysteines) - Hydrogen bond
→ Weaker than covalent bonds, important for secondary structure - Dipole-dipole interaction
→ Attraction between polar side chains - Intermolecular forces (Van der Waals) (weakest)
→ Temporary, induced dipoles between nonpolar groups
