Topic 6 Flashcards
Indicating the Time of Death
- Can be used to tell how long someones been dead for
- Depends on situation eg in water = harder to tell
Extent of Decomposition
- First Couple Hours - first hours of death/upto couple days
- Rate increases if temperature is higher and more oxygen available
Why are Microorganisms involved in decomposition
- Work to break down Organic Matter by secreting enzymes
- Carbon Compounds are recycled
Body Temperature during Death
- Alive, heat = metabolic reactions
- Cools 2 degrees every hour after death
- Factors affect this such as clothing
Forensic Entomology
-Finding out type of insects/microorganisms on body
Stages of Succession after Death
-Type of bacteria indicates period of death
Degree of Muscle Contraction after Death
- Rigor Mortis - stiffening of muscles
- muscles need ATP - attach the myosin head from the actin after contraction
- Anaerobic Respiration, lactic acid, glucose used up
Common Features in Euk and Pro Cells
- Plasma Membrane
- Cytoplasm
- DNA
- Ribosomes
DNA in Prokaryotes (Non-Living)
- Circular molecule in Cytoplasm
- Some smaller loops = Plasmids
- Bacteria - Plasmid Exchange
- eg Immunity Spread
Capsule Function
-Enable Prokaryotes to attach surfaces
Flagella Function
-tail like used for locomotion - in some pro.
Pili Function
-used to exchange genetic material during conjugation (type of reproduction)
Fimbriae Function
Used to attach host cell
Virus Structure
- nucleic acids
- Surrounded by protein called capsid
- Smaller then bacteria
What is DNA Profiling and when is it used
- Technique used for analysing samples of DNA
- Specific DNA patterns used to identify people, family, diseases etc
- Can be used in Crime Scenes
How do Scientists do DNA Profiling
-Order up all the Nucleotides, then compare to the existing DNA
Polymorphisms?
- Part of genomes that vary greatly
- used to distinguish between individuals and groups
Why is Polymerase Chain Reaction Used
-Increase DNA sample size
Polymerase Chain Reaction Steps (PCR)
- DNA heated to 96C = denatured strands to make them single
- Cooled to 60C to allow primers to anneal strands of DNA
- Heated to 72C so Taq Polymerase can work at optimum conditions = Extends nucleotide chains
- Repeated 25-35 times
What is a Primer
short lengths of DNA which free nucleotides can attach too
Why is Gel Electropheresis used?
-Separates DNA fragments according to size (number of base pairs)
Gel Electropheresis Steps
- DNA loaded into wells full of agarose gel
- Electric current passed through
- Negative charged DNA moves through to + electrode
- Smaller fragments move faster
- DNA ends up arranged in bands - similar strands together
Examples of Obtained DNA
-Hair, Skin, Saliva (Contains body cells)
How is DNA extracted from cells
- Nucleus extraced and isolated from cellular matter
- Using Detegents
Taq Polymerase
- DNA polymerase which attaches nucleotides to a single strand of DNA.
- Optimum Temperature is 72C
3 reasons why DNA application (Profiling) is used
- check relatedness of people
- risk of genetic disease
- identify potential criminals
What does HIV inhibit
-The immune System
Structure of HIV (4 bits)
- Capsule
- RNA
- Enzymes (reverse transcriptase/integrase)
- Viral Envelope
Capsule in HIV role
- Inside the centre of HIV
- Contains Genetic Material and Enzymes
RNA in HIV role
- Two strands of RNA
- Inside capsule
Enzymes in HIV role
- Reverse Transcriptase and Integrase
- Help with infection
Viral Envelope in HIV role
- Capsid enclosed by this
- Glycoproteins on surface
- Bind to surfaces of T helper cells to infect cells
HIV Replication 6 steps
1) Bind to T Helper Cells
2) Release of Capsid
3) Reverse Transcriptase
4) Integrase
5) Expression
6) Release of HIV
HIV Replication step 1 - Bind to T Helper Cells
-HIV is binded to t Helper cells via glycoproteins
HIV Replication step 2 - Release of Capsid
- Capsid injected into T Helper Cells
- Enzymes RT and I are released into cell
HIV Replication step 3 - Reverse Transcriptase
- Converts single stranded RNA from HIV into Double stranded DNA
- Moves into the Nucleus
HIV Replication step 4 - Integrase
-Inserts HIV DNA into T helper cells
HIV Replication step 5 - Expression
- Genes of HIV DNA are expressed in T helper Cells
- HIV Proteins synthesised
- new HIV RNA is made
HIV Replication step 6 - Release of HIV
- New HIV viruses released by T helper Cells
- T Helper cells die
- More cells infected
What is Aids
-Caused by HIV infection
Cause of Aids
- When T helper cells die - more infected cells
- Immune system weakened
- Makes it highly susceptible to infection by other pathogens (Aids)
Symptoms of Aids
- Flu (chills and fever) - 4 weeks of infection
- More vulnerable to infections
- Can take upto 10 years to develop
What is TB?
-caused by Myobacterium Tuberculosis, bacteria effects the lungs
How is TB spread?
- spread by air droplets
- person breathes in or sneezes
How does the immune system try and prevent TB
- Phagocytosed by Macrophages
- DOESNT kill bacteria
- Bacteira lies dormant in macrophage
How is TB activated
- when immune system is weakened
- gives bacteria time to reactivate and infect them with TB
Symptoms of TB
- Persistent and Violent coughs
- Night sweats
How can TB be treated
-course of antibiotics
Sequence of Events for TB infection
1) Person breathes in droplets
2) bacteria enters lungs
3) Bacteria phagocytosed by macrophage
4) M.Tuber lies dormant in Macrophage
5) Person immune system weakens, Bac activates causing TB
