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Science 4M1 > SB3cii-SB3k > Flashcards

SB3cii-SB3k Flashcards

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Biology 101 flashcards
1
Q

How to do DNA extraction?

A

(Check notebook notes).

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2
Q

What is a polypeptide chain?

A

Many amino acids joined together that make up a protein.

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3
Q

What is protein synthesis?

A

The creation of proteins using instructions from the DNA.

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4
Q

Which processes are involved in protein synthesis and where do they occur?

A
  1. Transcription (occurs in the nucleus)
  2. Translation (occurs on the ribosomes in the cytoplasm)
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5
Q

What is mRNA?

A

Messenger RNA is a single-stranded molecule that contains 4 different bases (A, C, G, U).

(Check book p.58 for diagram)

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6
Q

What happens during transcription? (6 steps)

A
  1. DNA unwinds.
  2. Hydrogen bonds between the bases break and DNA unzips.
  3. RNA polymerase will create the mRNA by adding free RNA bases (nucleotides) on the template strand of DNA using the complementary base-pair rule (C-G, A-U, etc).
  4. Once the entire instruction is copied by RNA polymerase and the mRNA is created, mRNA detaches from the DNA.
  5. mRNA leaves the nucleus and goes to the cytoplasm.
  6. DNA zips up again and rewinds.
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7
Q

What is tRNA?

A

Transfer RNA is a single-stranded molecule which is folded up and contains 4 different bases (A, C, G, U).

(Check notebook and book p.59 for diagram)

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8
Q

What is the job of tRNA?

A

To carry the correct amino acid to the ribosome for the making of the protein.

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9
Q

What happens during translation? (9 steps)

A
  1. mRNA binds on the ribosome in the cytoplasm.
  2. The ribosome reads the mRNA 3 bases (or one codon) at a time.
  3. The correct tRNA arrives carrying the correct amino acid with it.
  4. The anticodon of the tRNA will bind with the codon of mRNA using the complementary base-pair rule.
  5. The tRNA waits until another tRNA arrives.
  6. The amino acids are joined together by peptide bond starting the polypeptide chain.
  7. The previous tRNA then leaves.
  8. The ribosome will keep reading the mRNA until the end where it will find a STOP codon.
  9. Once translation is finished, the polypeptide chain will fold in the correct shape of the protein.
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10
Q

What is mutation?

A

A change in the sequence of bases in the DNA.

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11
Q

What are the 3 types of mutation?

A
  1. Substitution
  2. Deletion
  3. Addition
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12
Q

Why are deletion and addition more dangerous than substitution?

A

Substitution is the least dangerous mutation since it might not even have an effect on the phenotype because the new base could create a different triplet that codes for the same amino acid which would then there would be no problem in the folding of the polypeptide.

Deletion and addition can be very dangerous since they will result in a different protein that will carry different instructions.

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13
Q

What are mutagens?

A

Any chemical or radiation that can cause mutations (e.g. gamma rays, X-rays, UV rays).

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14
Q

What happens during deletion?

A

A base is deleted then the bases will shift to cover the gap. This causes a different base sequence so different triplets which causes a different amino acid sequence leading to a different polypeptide chain. This will create a different protein with the wrong shape that could be non-functional or give different instructions.

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15
Q

What happens during addition?

A

One or more bases are added during DNA replication so the bases need to shift to make room for the new base. This causes a different base sequence so different triplets which causes a different amino acid sequence leading to a different polypeptide chain. This will create a different protein with the wrong shape that could be non-functional or give different instructions.

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16
Q

What happens during substitution?

A

When one or more bases are substituted for a different one, which affects only the triplet and all the rest remain the same. This will cause a slight change in the shape of the protein and might not work properly creating some problems. However, if the new base creates a different triplet that codes for the same amino acid, then there is no problem in the folding of the polypeptide so the protein will be functional and remains the same (silent mutation).

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17
Q

What happens if mutation creates a STOP codon?

A

The protein remains incomplete and non-functional.

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18
Q

What is non-coding DNA?

A

DNA that doesn’t code for a protein.

19
Q

What can mutation in non-coding DNA cause?

A

Mutations in some non-coding parts can cause the RNA polymerase not to be able to bind correctly on the DNA and create less mRNA and so less protein.

In some other non-coding parts the RNA polymerase will bind better and produce more mRNA so more protein.

20
Q

What are the 3 laws of inheritance that Mendel found in his work?

A
  1. Each gamete receives only one factor for a characteristic.
  2. The version of a factor that a gamete receives is random and does not depend on the other factors in the gamete.
  3. Some versions of a factor are more powerful than others and always have an effect in the offspring.
21
Q

What are genes?

A

Genes are pieces of DNA in our chromosomes and are each responsible for a certain characteristic (e.g. colour of eyes).

22
Q

What are alleles? How many are there?

A

Different forms of the same gene. There are at least 2 alleles of every gene.

23
Q

What is monohybrid inheritance?

A

The inheritance of one gene at a time.

24
Q

What is a dominant allele?

A

A dominant allele is an allele that overrides equivalent recessive alleles. They always show the characteristic and are shown with a capital letter (e.g. “B”).

25
Q

What is a recessive allele?

A

A recessive allele is an allele that is overridden by an equivalent dominant allele and remains hidden. It can only be expressed and show the characteristic when it is found with another recessive allele and is shown with a small letter (e.g. “b”).

26
Q

What does heterozygous mean?

A

Two different alleles for one particular gene (e.g. Bb).

26
Q

What does homozygous mean?

A

Two identical alleles for one particular gene (e.g. BB or bb).

27
Q

What is codominance?

A

When both alleles for the characteristic are dominant and they are both expressed.

28
Q

Which are the dominant and recessive blood group alleles?

A

Dominant: IA, IB

Recessive: IO

29
Q

What are sex-linked genetic disorders?

A

Sex-linked genetic disorders are disorders that show a different pattern of inheritance in men and women and occur when the faulty allele is located on theXchromosome.

(Also check notebook for extra notes)

30
Q

Why is it less likely for women to get sex-linked genetic disorders?

A

If the faulty allele is recessive, then the females could be either carriers, healthy or diseased and they would require to inherit both disorder alleles to be diseased.

The males will either have the disease or not since they cannot be carriers because they only have one X chromosome.

31
Q

How does colour blindness occur?

A

Caused by a recessive allele on the X chromosome. Colour vision is due to the 3 types of light receptors, the cones found in the eye. The ability to see light is the result of multiple genes and mutation in these genes affect the ability to see and distinguish different colours.

32
Q

What is haemophilia and why can women not get this disease?

A

Haemophilia is caused by a recessive allele on the X chromosome and it is when blood does not clot normally so bleeding is very difficult to stop.

Women cannot get this disease since the zygote does not survive during pregnancy.

33
Q

What is the HGP?

A

The Human Genome Project is a huge project for which many scientists from different countries have worked together as a team. It is a map of all our genes in our DNA which allows scientists to know on which chromosome and at which exact location each gene is found.

34
Q

What does the HGP allow scientists to do? (3 things)

A
  1. Indicate if a person has a risk to develop a certain disease that is hereditary.
  2. Find out if a person carries a specific genetic disease.
  3. To develop personalised drugs for people that cannot use the existing drugs. This is because our DNA determines how our body will react to the drug.
35
Q

What is variation?

A

The difference in the characteristics within the same species and different species.

36
Q

What are the two types of variation?

A
  1. Genetic variation
  2. Environmental variation
37
Q

What is genetic variation?

A

Variation that is caused by the different mixture of alleles that organisms inherit from their parents (such as eye colour, shape of nose etc.)

38
Q

What is environmental variation?

A

Variation that is cause by different environmental factors such as pierced ears and having a tattoo.

39
Q

What are characteristics that are changed by the environment called?

A

Acquired characteristics.

40
Q

What are the two groups of variation?

A
  1. Continuous variation
  2. Discontinuous variation
41
Q

What is continuous variation?

A

Continuous variation in characteristics, are usually a result of the environment and are called acquired characteristics. If data for continuous variation are plotted they show a bell-shaped, normal distribution curve (e.g. height, mass).

42
Q

What is discontinuous variation?

A

Discontinuous variation in characteristics, are usually caused by the instructions within the cells and are called genetic variations (e.g. blood group, gender of organisms).

Science 4M1 (7 decks)

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