Chapter 13 and Chapter 16 Test Flashcards
Define biotechnology
Various techniques used to determine genetic disorder in individuals
What are the four techniques of biotechnology?
- DNA sequencing
- Polymerase Chain Reaction (PCR)
- DNA profiling
- Genetic Probes
Which technique determines the order of nucleotides on a DNA strand?
DNA sequencing
What does a typical DNA strand have?
It has the correct base pairs matched
- A-T
- C-G
What can happen if the base pairs aren’t matched properly?
If the base pairs don’t match, then a mutation can occur
What will scientists use a sequenced genetic disorder to do?
They will match the genetic disorder, such as sickle cell anaemia, with someoneone who “potentially” has this disorder or compare a genetic disease with a “normal” sample
What is DNA sequencing used for?
To make a person’s DNA profile such as, finger prints or mapping their genome
Give an example of DNA Sequencing and explain it
Maternity and paternity tests. They use this test to determine whether the parents nucleotides (DNA sequences of bases) match those of those of the child
How is a person’s profile worked out?
- PCR will be used to amplify a sample
- A DNA profile can be created from a very tiny sample of DNA
What is PCR used for?
To create many copies of one sample
What is a primer?
A short piece of single-stranded DNA
What is added as an “anchor point” for the DNA polymerase to start replication?
A primer
What is a primer added for?
To be an anchor point for the DNA polymerase which will start replication
How many cycles of PCR will occur?
30 - 40 cycles
What is the first step of PCR?
Denaturing
Describe denaturing
- Separating complimentary strands of DNA by using heat
- The temperature used is 96 degrees
What is the second step of PCR?
Annealing
Describe annealing
- Adding a primer, which is a small strand of DNA, which binds to the complementary base sequences. This is replicating the DNA strand
- DNA strand is heated and cooled (54 degrees)
What is the third step of PCR?
Extension/Elongation
Describe extension/elongation
- DNA polymerase makes a copy of DNA by binding to the strand
What is the name for the enzyme used in PCR?
Taq polymerase
Describe the role of Taq polymerase
Attaches to the primer on the DNA strand which synthesizes a new DNA strand/creates a complementary strand
Explain why taq polymerase is a suitable enzyme for PCR
Because it is capable of withstanding high temperature, so it will not denature in the process of PCR
what is fossil evidence?
- it shows organisms which previously existed but are now extinct e.g. dinosaurs
- It shows how species do not last forever
what is a fossil?
- a fossil is the preserved remains of a once living organism
What are some examples of fossils?
- Footprints
- Burrows
- Faeces
- Impressions of all or part of an animal, plant, bones (teeth) and shells
What are artifacts?
-Artifacts are objects that have been deliberately made by humans
What are some examples of artifacts?
- Stone tools
- Beads
- Carvings
- Charcoal from fires
- Cave painting
What is needed for fossils to be preserved?
- Quick burial of specimen/covered quickly by sediments
- Buried in soils of low pH for soft tissue
- Buried in alkaline soil for bones
- Rapidly buried in ice
- Rapidly buried in volcanic ash
- Specimen needs to be not disturbed by earth movements
Describe sediment in terms of fossil formation
An animal is buried by sediments, such as volcanic ash or silt, shortly after it dies. Its bones are protected from rotting by the layer of sediment
Describe layers in terms of fossil formation
More sediment layers accumulate above the animal remains and minerals, such as silica (compound of silicon and oxygen) slowly replace the calcium phosphate in the bones
Describe movement in terms of fossil formation
Movement of tectonic plates, or giant rock slabs that make up Earth’s surface, lifts up the sediments and pushes the fossil closer to the surface
Describe erosion in terms of fossil formation
Erosion from rain, rivers and wind wears away the remaining rock layers. Eventually, erosion or people digging for fossils will expose the preserved remains
What is the first step in an excavation dig?
Scientists investigate the area and mark out sections to be exposed
What is the second step in an excavation dig?
They use small hand held tools to remove soil gently so they don’t destroy any material
What is the third step in an excavation dig?
Soil that is removed is then sieved so any small or large fragments are caught and looked at
What is the fourth step in an excavation dig?
Anything found will be labelled and catalogued
What is absolute dating?
The process of placing an actual age of a fossil in years
What is potassium argon dating based on?
It is based on the decay of radioactive potassium to form calcium and argon
What is potassium a mixture of? What does it have a number of?
Potassium is a mixture of 3 different forms. It has a number of different neutrons in the nucleus called an isotope
Where is potassium produced?
The radioisotopes of potassium is produced in volcanic eruptions and thus is trapped in rock
What is the half life of potassium?
1.3 billion years
What does potassium decay into?
The rare stable gas of argon
What is an advantage of potassium argon dating?
Can date materials up to 4 billion years old
What is a limitation of potassium argon dating?
Must have suitable rocks like volcanic/igneous rocks to use this method
What is carbon 14 dating based on?
Carbon 14 is based on the decay of the radioactive isotope of carbon 14 (carbon 14 to nitrogen)
Where is carbon produced?
Carbon is produced in the upper atmosphere
Where is carbon taken in?
Carbon is then taken into living organisms as organic matter (plants) and incorporate carbon 14 through photosynthesis
How does C14 become part of an animal’s tissues?
When an animal eats the plant C14 becomes apart of the animal’s tissues
What happens to the C14 in an animal’s tissues when they die?
When an animal dies the C14 ceases and will start to decay at a steady rate
What is the half life of Carbon 14?
5730
Once C14 decays what does it become?
It will lose carbon 14 and become nitrogen 14
How can the age be estimated through Carbon 14 dating?
By measuring the amount of radiation in a sample, the ratio of Carbon 14 to Nitrogen 14
Give one advantage of carbon 14 dating
Useful for dating artifacts that contain organic matter
Give one limitation of carbon 14 dating
3 grams of organic matter is needed to use this method
What does AMS stand for?
Accelerator Mass Spectometry
What is AMS used for?
To date samples as small as 100 micrograms
What is counted in the AMS dating method?
Numbers of each isotope of carbon can be counted
How can AMS date cave paintings?
AMS can date cave paintings accurately from tiny samples of pigments
What do pigments from cave paintings contain?
These pigments contain tiny matter such as charcoal, milk, honey, blood or soil
Give an advantage of AMS
You only need 100 micrograms of the sample
Give a limitation of AMS
Only useful for materials up to 70,000 years
What does each ring of a tree cut in half represent?
Each ring of a tree cut in half represents one years growth
What will trees differ in and why?
Trees will differ in width according to how good/bad the rain season was
What ensures a thick width on a tree?
The thicker the width could mean a good rainfall season
Why would a tree have a small width?
If the width is small then it could mean a low rainfall season
What is an advantage of dendrochronology?
Good for calculating actual ages of fossil wood
What is a limitation of dendrochronology?
It is only useful for wood younger than 9000 years
Requires fossils of the same species
What is relative dating?
Relative dating is the process of establishing an approximate age based on comparing it to other known fossils. Scientists will determine whether the artifacts or fossil is older or younger than another sample
What is stratigraphy?
Stratigraphy is the study of layers which consist of rock, soil, fossils and artifacts
What are the two methods of stratigraphy?
Principle of Superposition
Correlation of Rock Strata
What is the principle of superposition?
the principle of superposition states that rock layers at the bottom of a sequence are older than the ones on top
What do deeper strata (layers) indicate?
The deeper the strata (layers) the fossil at the bottom was first deposited
What is the problem with the principle of superposition?
The problem with this principle is that many rock layers don’t remain in the order they were originally laid down
What is the correlation of rock strata?
Matching layers of rock from different parts of the world
How can matching strata be done?
Matching strata can be done by examining the rock itself and by studying the fossils it contains. It can be assumed both objects are the same age
What are index fossils?
Certain types of fossils and preserved remains that can also assist in relative dating
What is an important thing to know about index fossils?
Index fossils are of distinctive appearance, have a short time span, and have a broad geographical distribution
What era are trilobites apart of?
Palaeozoic Era
Give an example of an Index fossil
Trilobites
What are trilobites?
A fossil group of extinct marine arthropods
What do bones buried in the same environment absorb?
Bones buried in the same environment absorb fluorine ions at the same rate
What happens when a bone is left in soil?
When a bone is left in soil, fluoride ions, which are present in the water of the soil, replace some of the ions in the bone itself
What happens if bones in a particular deposit contain the same amount of fluorine?
It can be assumed that they are of the same age
How can a person tell the older a fossil is?
The older a fossil is, the more fluorine it contains
What are three problems with fossil record
Fossils may be:
- Not recognised or only fragments
- Buried too deep to find
- Located in places impossible to get to
