Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > 6C > Flashcards

6C Flashcards

1
Q

what are decomposers

A

-they are microorganisms which are bacteria or fungi that break down dead organisms
- they secret enzyme that break down large substances into smaller substances and release waste products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

state the steps of carbon cycle

A

1- decomposers produce carbon dioxide and methane which is released into the atmosphere
2- plants absorb the carbon dioxide in the atmosphere and fix the carbon into carbohydrates during photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how can DNA profiles be created

A
  • isolating a sample of DNA ex. saliva, skin, hair or blood
  • producing more copies of DNA using the polymerase chain reaction (PCR)
  • carrying out gel electrophoresis on the copies of DNA
  • analyse the bands of DNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is PCR and where is it carried out

A
  • it is described as an method of DNA replication
  • DNA amplification is when PCR produces many copies of of a piece of DNA
  • the process is carried out in a thermal cycler which provides the optimal temperature for each stage and controls the length of time spent at each stage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what does each PCR reaction require

A
  • DNA or RNA to be amplified
  • primers
    -DNA polymerase
  • free nucleotides which enables the construction of new DNA or RNA
  • buffer solution ensure the optimum pH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the three main stages of the PCR reaction

A
  • Denaturation
    • the double-stranded DNA is
      heated at high temperature to
      break the hydrogen bond that
      holds the two strands
  • Annealing
    • the temperature is decreased for the primers to anneal to the ends of the strand
  • Extension
  • the temperature is increased to 72 °C since its the optimum temp. for taq
    at the end a single PCR cycle is completed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what happens after PCR

A

DNA is treated with
- restriction endonuclease enzyme and fluorescent tag are added for gel electrophoresis
* restriction endonuclease enzymes break down the DNA strand into fragments of different length
* fluorescent tag enables the DNA to be seen under UV light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is gel electrophoresis

A

its a technique used to analyse the fragments of DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how is gel electrophoresis proceeded

A
  • the fragments are inserted at the far end of an agar gel
  • when a current is passed through DNA is negatively charged due to the phosphate group so when placed in a electric field molecules will move towards the anode
  • molecules are separated due to sizes which will move at different rate, the smaller the masses the faster they move
  • Probes are added, after when the UV light is shone onto the paper producing a pattern of bands to be compared to the control
  • probes are a single-stranded DNA sequences that are complementary to the regions of interest
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is VNTR

A
  • restriction endonuclease enzyme cuts the sections of repeated DNA bases known as variable number tandem repeats (VNTRs)
  • the fragments will differ in length due to different number of repeats in the VNTR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how is the DNA profile used to compare

A
  • the DNA profile of a control is compared with different DNA profiles
  • the more the bands that match between individuals the greater the genetic similarity
  • the greater the number of VNTR examined the more reliable
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

when can DNA profiling be used

A
  • can be used in selective or captive breeding programmers to breed organisms that are not closely related
  • when breeding with closely related genes its called inbreeding which leads small gene pool
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is a forensics

A
  • its the use of science to investigate criminal activities which involves determining the time of death(TOD)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are the factors that are needed to be established to determine the time of death

A
  • extent of decomposition
  • stage of succession
  • Forensic entomology ( the study of insects)
  • body temperature of the deceased
  • the degree of muscle contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does the extent of decomposition establish TOD and what are the factors that affect the decomposition

A

By looking at the appearance of a body it’s seen that:
- decomposers break down cells and tissue, the skin colour can indicate TOD which will often appear green at this stage
- the decomposers will break down tissues of the organs which will produce gases such as methane and will lead to bloating, the skin will blister and fall off
- the process will continue until only the skeleton remains
- after a few decades or centuries the skeleton will disintegrate until nothing remains
- the decomposition will be affected by factors such as temperature and oxygen, the decomposition would be slower at anearobic conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the stage of succession in death

A
  • succession is known that the type of organisms will be changing overtime while in death all new arriving organisms will stay
17
Q

How does the stage of succession help to estimate TOD

A
  • the bacteria will immediately after TOD be found in and on the body
  • decomposers will create ideal conditions for flies to lay eggs and their larvea to hatch
  • as more soft tissue is consumed by the fly larvae it creates a new condition for beetles to establish
  • when the tissues dry out the flies will leave the body as they prefer moist conditions but beetles will remain and will decompose dry tissues until the body is completely decomposed
  • the succession stages will differ depending on where the body is located: buried in soil, burried in coffin or under water
18
Q

How does Forensic entomology help to determine TOD

A
  • a dead body provides an ideal habitat for many species of insect where they will colonise the body at different times after death
  • insects can provide information from stage life cycle:
    *Larvae hatch after 24 hours, other insects have longer life cycles
19
Q

What are the factors that might affect the progression of insect life cycle

A
  • drugs that may be present in the body
  • humidity of the surroundings
  • oxygen availability
  • temperature
20
Q

how does body temperature help to determine TOD

A
  • metabolic reactions provide heat when a stop person dies the metabolic reactions will stop so the temperature of the body will drop until it reaches the temperature of the surroundings this is known as algor mortis
  • body temperature decreases by 1.5-2.0 °C per hour
21
Q

what are the conditions that affect the rate at which body heat is lost

A
  • air temperature
  • surface area : volume ratio
  • presence of clothing
  • percentage body fat
22
Q

what happens to the muscles after death and how does it help to determine TOD

A
  • rigor mortis occurs which is when the muscles will start to contract after 4-6 hours of death which will become stiff
23
Q

how does rigor mortis come

A
  • no more oxygen will reach the body which will cause the muscle to respire anaerobically which produce lactic acid
  • the increase of the production of lactic acid will cause the pH to decrease and denature the enzymes that produce ATP
  • without ATP the protein filaments wont be able to detach or to bind which leads to locking contraction of the muscle
  • the process is affected by the level of the muscles and the temperature of the surrounding the higher the temperature the higher the rate of rigor mortis
24
Q

how do muscles contract

A
  • the contraction of muscles occurs due to two protein called:
  • myosin
  • actin
  • myosin will bind to actin which causes it to bend
  • ATP is required to detach the proteins

Biology (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions