Topic 3 Summary (Voice of the Genome) - A-Level Biology A (2015) Salters-Nuffield
11 views 0 purchase
Course
Voice of the Genome
Institution
PEARSON (PEARSON)
Book
Salters-Nuffield Advanced Biology
This document offers a selection of summary notes on the chapter: Voice of the Genome. This is based on textbook A-Level Biology A (2015) Salters-Nuffield
Topic 4 Summary (Biodiversity and Natural Resources) - A-Level Biology A (2015) Salters-Nuffield
Topic 2 Summary (Genes and Health) - A-Level Biology A (2015) Salters-Nuffield
All for this textbook (5)
Written for
A/AS Level
PEARSON (PEARSON)
Biology A
Voice of the Genome
All documents for this subject (1)
Seller
Follow
justkarima
Content preview
GEN Revision Notes
[Topic 3] Voice of the Genome
, A Level Notes GEN: Protein Transport/Fertilisation/Stem Cells Biology
Protein Synthesis + Transport
1) Transcription of DNA to mRNA inside nucleus
2) Travels to ribosomes on rER where mRNA is translated into protein
3) Proteins enter and move through rER assuming 3D shape en route
4) Vesicles pinch off rER containing protein
5) Vesicles fuse to form flattened sacs of the Golgi Apparatus
6) Proteins are modified here (e.g. sugars added)
7) Vesicles pinch off, travel and fuse with cell surface membrane
8) Release protein (such as extracellular enzymes) via exocytosis
Stages of Fertilisation
1) Receptors on sperm membrane make contact with the zona pellucida
2) Hormones released by ovum cause acrosome to swell
3) Vesicles with digestive enzyme in acrosome fuse with sperm cell surface membrane
4) Exocytosis of enzymes occurs
5) Digestive enzymes from acrosome break down follicle cells and zona pellucida
6) Sperm fuses with ovum membrane; this allows sperm nucleus to enter ovum and fuse with
egg nucleus
ACROSOME REACTION CORTICAL REACTION
→ Acrosome in head of sperm swells, fuses with cell surface → Ovum receptor detects sperm, then releases chemicals
membrane, releases digestive enzymes → Zona pellucida thickens
→ Breaks down zona pellucida → Polyspermy prevented
SIMILARITIES DIFFERENCES
✓ Both involve the release of substance (acrosome in sperm, Zona pellucida broken down in AR, but thickens in CR
chemicals in ovum) AR allows entry of sperm nucleus, CR prevents entry of sperm
✓ Both have specialised lysosomes (acrosome in sperm, cortical
granules in ovum)
✓ Both triggered by stimulus
Totipotent All 216 cell types Embryonic stem cells (early zygote)
Pluripotent Most, but not all Adult stem cells; bone marrow; hair; muscle; in blastocyst
Multipotent/ Unipotent Only some cell types Neural cells; cord blood; cardiac cells; bone marrow
Digestive tissue, nervous tissue, cardiac tissue
Unspecialised cells have no limit to number of divisions → Hayflick Limit
Embryonic Stem Cells Adult Stem Cells
✓ Totipotent; differentiate into any cell type ✓ No rejection; genetically identical
✓ Treat a variety of diseases ✓ No immunosuppressants required
✓ Repair any damages tissue ✓ Less risk of infection
✓ Easier to obtain
Expensive Multipotent; only some diseases cured
Chance of rejection Religious issues (imitating God, etc.)
Destruction of (embryo) potential life
Regulatory body; cost, source, age of embryo, illegal cloning
Implications if discarded IVF embryos used
Plant Reproduction:
How stem cells become specialised: The sperm cells of a flowering plant are contained in
pollen grains. Pollination occurs when pollen grains are
1) Chemical stimulus (e.g. hormone) transported from anthers to stigmas. After the pollen
2) Activates some genes lands on the stigma, a tube grows from the pollen grain
3) Allows transcription of DNA → mRNA through the style of the ovary. Inside the ovary are
4) Translated into protein at ribosomes ovules. Each ovule contain an egg. Sperm cells within
5) Causes structural change of cell the pollen grain move down the pollen tube and into the
6) Cell because differentiated and specialised for a particular function ovule. Fertilization occurs as one of the sperm cells fuse
with the egg inside the ovule.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller justkarima. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $4.52. You're not tied to anything after your purchase.
