DNA Flashcards

1
Q

What is DNA?

A

DNA is the molecule that stores and encodes all the information in an organism, such as which protein to make and how to make them.

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2
Q

What does DNA stand for?

A

DNA stands for deoxyribonucleic acid. It has a double helix made up of two strands twisted together.

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2
Q

What are the four nucleotides of DNA?

A

The four nucleotides of DNA are adenine, cytosine, guanine, and thymine. A pairs with T and C with G. they are complementary to one another.

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2
Q

What are nucleotides?

A

Nucleotides are building blocks of DNA and RNA molecules that contain the cell’s genetic code.

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3
Q

DNA strands are held together by what?

A

DNA strands are held together by hydrogen bonds.

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4
Q

What are the five enzymes in DNA replication:

A

DNA Helicase, DNA Polymerase, DNA Topoisomerase, DNA Ligase, and DNA Primase

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5
Q

What does DNA Helicase do?

A

DNA helicase unwinds the DNA helix during DNA replication by breaking the hydrogen bonds.

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6
Q

What does DNA Primase do?

A

DNA primase creates a short RNA primer needed to start replication.

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7
Q

What does DNA Polymerase I do?

A

DNA polymerase I is an enzyme that removes RNA primers and replaces them with the appropriate nucleotides during DNA replication.

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8
Q

What does DNA polymerase III do?

A

DNA polymerase III is an enzyme responsible for making complementary strands of DNA during DNA replication

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9
Q

What does DNA ligase do?

A

DNA ligase is an enzyme that connects two fragments of DNA to make a single fragment.

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10
Q

What does DNA topoisomerase do?

A

DNA topoisomerase breaks (cuts/untangles) and rejoins the DNA double helix to relieve tension caused by the opening of the helix. It can heal and break bonds.

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11
Q

What is a lagging strand?

A

The lagging strand is a strand that is replicated in short fragments and away from the replication fork, during the replication of 3’ to 5’ strand.

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12
Q

What is a leading strand?

A

A leading strand is the strand that is synthesized continuously in the 5’ to 3’ direction, in the direction of the replication fork.

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13
Q

What are okazaki fragments?

A

Okazaki fragments are DNA fragments that are synthesized in short stretches on the lagging strand.

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14
Q

What is a chromosome?

A

A chromosome is the entire collection of a cell’s DNA. It contains all the cell’s genetic information.

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15
Q

What is DNA replication?

A

DNA replication is the process in which a cell’s entire DNA is copied.

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16
Q

When does DNA replication occur?

A

DNA replication occurs during the S (synthesis) phase in the cell cycle before to cell division.

17
Q

What’s the difference between eukaryotic cells and prokaryotic cells?

A

Eukaryotic cells has linear DNA, has several chromosomes, the nucleus is present, and plant, fungi, and animal cells are eukaryotic cells.

Prokaryotic cells has a circular DNA, has one chromosome, the nucleus is absent, and bacteria and green-algae are prokaryotic cells.

18
Q

What is a template strand?

A

A template strand is the strand that acts as a template for RNA synthesis, guiding the information of mRNA.

19
Q

What is a complementary strand?

A

A complementary strand is the nucleotide of DNA and RNA that pairs up with another strand through specific base pairings.

20
Q

What is RNA?

A

RNA is a ribonucleic acid. It is a nucleic acid that is present is most living organisms and viruses.

21
Q

What are the nucleotides of RNA?

A

Adenine, Uracil, Guanine, and Cysotine. A pairs with U and C with G.

22
Q

What are the chemical components of RNA?

A

Ribose sugar, phosphate groups, and nitrogenous bases (A, U, C, G).

23
Q

What is the role of RNA?

A

RNA is the messenger carrying genetic information from DNA and helps make proteins in the cell.

24
Q

What are the three types of RNA?

A

mRNA, rRNa, and tRNA.

25
Q

What does mRNA do?

A

mRNA carries genetic information from the DNA in the nucleus and translates the information into sets of codons.

26
Q

What does tRNA do?

A

tRNA is responsible for transferring amino acids to the ribosome during protein synthesis.

27
Q

What does rRNA do?

A

rRNA forms the structure of ribosomes and helps assemble proteins in the cell.

28
Q

What is the difference between DNA and RNA?

A

DNA is a double stranded helix, the nucleotides for DNA are A, T, C, and G, DNA can replicate itself.

RNA is a single stranded helix, the nucleotides for RNA are A, U, C, and G, RNA is mostly dependent on DNA for its synthesis.

29
Q

What is a codon? Where does it come from and why is it important?

A

A codon is a three-letter genetic sequence found in DNA and RNA that specifies which amino acid will be added next during protein synthesis or signals a stop to the process.

A codon is formed during transcription, where a portion of DNA is copied into mRNA.

Codons are important because they tell the cells which amino acid to add next during protein synthesis, making sure proteins are built correctly. Some codons also signal when to start and stop the entire protein-making process.

30
Q

What is translation and what is the process of translation?

A

Translation is the process where the code on mRNA is used to build proteins

Initiation: The ribosome attaches to mRNA and starts reading it at the start codon (AUG).

Elongation: The ribosome reads each codon on the mRNA, and matching tRNAs bring the correct amino acids, which are linked together into a protein chain.

Termination: When the ribosome hits a stop codon, it stops reading the mRNA, and the newly made protein is released.

31
Q

What is transcription and what is the process of transcription?

A

Transcription is the process of making RNA from DNA strand

Initiation, Elongation, Termination.
DNA to mRNA - mRNA takes the code from DNA and translates the information at the ribosome in the cytoplasms.

32
Q

What are introns?

A

Introns are non-coding sequences found in DNA or RNA, that are removed during RNA processing before the mRNA is translated into proteins.

33
Q

What are exons?

A

Exons are the coding portions of DNA or RNA, that have the instructions to build proteins.

34
Q

How do you read the genetic code and how do you identify it?

A

Genetic code can be read using the codon chart. To read a genetic code,

(transcription) the DNA is copied to mRNA.

(translation) mRNA guides assembly of amino acids into proteins.

(Codon Recognition) Ribosome reads mRNA in groups of three, called codons.

(Amino Acid Assembly) Each codon specifies an amino acid.

(Termination) Protein synthesis stops at stop codon.

35
Q

What is the central dogma of molecular biology?

A

The central dogma of molecular biology is a theory stating that genetic information flows only in one direction, from DNA to RNA, to protein, or RNA directly to protein.

36
Q

Information that is transferred from DNA to RNA to Protein

A

The flow of genetic information from DNA to RNA to protein is a fundamental concept in biology:

Transcription: DNA is copied into RNA by a process called transcription.

Translation: The RNA (specifically, messenger RNA or mRNA) carries the genetic instructions to ribosomes, where they are translated into proteins.

37
Q

How does gene expression work?

A

Gene expression is how genetic information is used to create proteins, starting with DNA being copied to mRNA, which is then used to build proteins.

38
Q

What is the difference between inherited and somatic mutations?

A

Inherited mutations are present in every cell of the offspring’s body, it is passed down from parent to offspring through germ cells (sperm and egg). Inherited mutations can be linked with genetic disorders or diseases that can affect multiple generations of a family.

Somatic mutations are not hereditary, because they do not affect germ cells, they can be found in a part of a body or tissue, they exist only in the tumor itself.

39
Q

What is a mutagen?

A

Mutagens are things in the environment that can change DNA. They can be physical (UV radiation from sunlight), chemical (tobacco smoke), or biological in nature (certain viruses).

40
Q

Are all mutagens bad?

A

Not all mutagens are harmful. While some can increase the risk of diseases like cancer, mutations can also be beneficial for evolution, driving genetic diversity and adaptation.

41
Q

What is the difference between point and frameshift mutations? (and their variations.)

A

With frameshift mutation, you can change an entire codon, and point gene mutation is where you can only change one gene.

A point mutation affects a single codon, a frameshift mutation affects many codons because the reading frame gets changed.