Hey guys! Welcome back to Biology with Gracie!
Today the topic focus is: IMMUNOLOGY - The Immune System & Non-Specific Defences
Immunology GCSE & A Level Specification Content
I have gone through all the GCSE specifications for AQA, Edexcel and OCR* and picked out the points related to protein synthesis, so you aware of what you need to know for your exams. The Word document and PowerPoint presentation attached below include this information in organised tables. Summary tables also include a scale which indicates the detail your specification requires you to know about protein synthesis.
Scale summary
Scale: 1 - 3
(1) Key details of protein synthesis not required to be learnt
(2) Some details of protein synthesis required to be learnt
(3) Most details of protein synthesis required to be learnt
The scale is explained in further detail in the attachments. Please be sure to like this post and comment below if you have used these documents and whether you have found them useful.
Word Document:
PowerPoint Presentation:
GCSE Content
Key points from all GCSE Biology & Combined Sciences Specifications:
For GCSE biology & combined sciences details of T cells & B cells are not required. Knowledge of how pathogens cause illness, non-specific physical and chemical defences & general information about the immune system is required.
Pathogens & Infection
Pathogen = Disease-causing viruses, bacteria, fungi or protists, which can infect animals and plants. Make you feel ill by damaging cells/ altering how they work.
Bacteria:
Small, living prokaryotic cells (1/100th size of body cells)
Reproduce rapidly inside body
Cause illness by:
Invading & destroying body cells
Releasing toxins (poisons)
Viruses:
Tiny (1/100th size of a bacterium)
Cause illness by taking over cell's DNA causing@
Cell to make toxins
Cell damage - new viruses released from cells.
Fungi:
Eukaryotic organisms
Single & Multi-celled
Protists:
Eukaryotic organisms
Many are free-living but some are pathogens
Non-specific defences: Chemical & Physical (& Microbial)
1) Physical
Skin
Skin - Barrier to pathogens.
Platelets - Form clot when skin is cut to prevent entry to pathogens.
Micro flora - Bacteria on skin that are part of our microbiome. Adapted to skin's habitat; compete with pathogens. (Microbial)
Nose
Hairs - Trap pathogens and prevent them going into throat.
Mucus - Traps pathogens.
Trachea & Bronchi/Lungs
Mucus - Traps pathogens. Produced by goblet cells.
Lined with ciliated epithelial cells - Cilia are tiny hair-like structures that move mucus up to throat. Mucus is then coughed out or swallowed to be destroyed in stomach.
2) Chemical
Stomach
Hydrochloric acid - pH2. Destroys pathogens taken in through mouth that then travel down oesophagus (food pipe).
E.g. Pathogens on food, drink or mucus from breathing passageways.
Lysozyme enzyme
Lysozyme enzyme in tears - destroys bacteria by breaking down cell walls.
Found in saliva and mucus also.
Immune System
White Blood Cells
Defence roles against pathogens:
Engulfing them - phagocytosis
Producing antibodies
Producing antitoxins
2 main types of WBC:
Phagocytes (non-specific) - Bind to & engulf pathogens.
Lymphocytes (specific) - Recognise antigens (specific proteins) on pathogen's surface.
Phagocytes
Phagocytosis
Phagocyte moves to pathogen.
Phagocyte releases cytoplasm surrounding pathogen.
Pathogen is enclosed in vacuole. Pathogen is broken down by enzymes.
Lymphocytes
Antibody Production
Every invading pathogen cell has a unique molecule called an antigen on its surface
Lymphocytes recognise the foreign antigen and produce proteins called antibodies to destroy the pathogens
1. Lymphocytes recognise the foreign antigen on an invading pathogen
2. Lymphocytes rapidly reproduce to make many specific antibodies that:
Cause cell lysis (pathogens burst)
Bind to pathogens & kill them
Cover the pathogens, sticking them together
3. Phagocytes then ingest the pathogen
Secondary Response
If the individual is infected with the same pathogen again 'memory' lymphocytes can remember the antigens from an infection by a previous pathogen and hence this results in a more rapid immune response; lymphocytes will rapidly produce the correct antibodies to kill it. This is immunity.
Antitoxin Production
Pathogens cause illness due to the toxins they release into our cells
Lymphocytes produce antitoxins to neutralise/counteract the toxins produced by the pathogen.
Antitoxins combine with the toxin to make a safe chemical.
Antitoxins are specific to a particular toxin, like antibodies are specific to a particular antigen.
Challenge yourself! Phagocytosis is included in A Level Biology specifications. The diagram below shows the stages of phagocytosis in the non-specific defence system.
I hope you find this post useful and enjoy my YouTube videos! You've got this!
See you soon,
Grace
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