Biology Unit 8 Flashcards

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Questions and Answers

Describe the structure of a nucleotide

A nucleotide consists of a sugar (deoxyribose), one of four bases (Cytosine, Thymine, Adenine, Guanine), and a phosphate.

Explain how nucleotides are arranged to make up a polynucleotide

Through a covalent bond between the phosphate group of one, and the third carbon atom of the pentose sugar in the next.

Name the four nucleotides found in DNA and explain how they differ

Cytosine, thymine, adenine, and guanine. They differ in their nitrogen-containing bases.

Give the two differences between DNA and RNA

DNA: Sugar is deoxyribose. Bases are A, T, C, G. RNA: Sugar is ribose. Bases are A, U, C, G. Signup and view all the answers

Describe the double-stranded helix of a DNA molecule

Two strands that wind around each other like a twisted ladder. Signup and view all the answers

Explain how the replication of DNA depends on specific base pairing

The bases that go together will attach when the original DNA molecule is split apart, creating a new one. A pairs with T, and C with G. New DNA is known as Daughter DNA. Signup and view all the answers

What are the two main stages of protein synthesis?

Transcription and translation. Signup and view all the answers

Describe transcription

The synthesis of RNA on a DNA template. Signup and view all the answers

Describe translation

The synthesis of a polypeptide using genetic information encoded in an mRNA molecule. Signup and view all the answers

Explain how genetic info is written as codons and translated into amino acid sequences

Codons are three base 'word' triplets. These triplets specify specific amino acids. Signup and view all the answers

Explain how transcription produces genetic messages in the form of RNA

Specialized proteins attach to the DNA strand and make a copy of the DNA sequence in the form of a molecule called messenger RNA (mRNA). mRNA encodes amino acid sequences. Signup and view all the answers

Describe the role of mRNA in getting the genetic message translated to the cytoplasm

mRNA is genetic messages from DNA. mRNA info gets translated into polypeptides. In eukaryotic cells, this process occurs in the cytoplasm. Signup and view all the answers

Explain the role of transfer RNA in the translation into polypeptides

tRNA is the translator for nucleic acid 'words' known as codons, to amino acid 'words' of proteins. Signup and view all the answers

Describe the structure and the role of ribosomes in the synthesis of polypeptides

Ribosomes consist of 2 subunits, one large and one small, each consisting of proteins and ribosomal RNA. Ribosomes are structures in the cytoplasm that coordinate the functioning of mRNA and tRNA and catalyze synthesis of polypeptides. Signup and view all the answers

Define mutagen and explain how mutation can change the meaning of genes

Mutagen: A chemical or physical agent that interacts with DNA and causes a mutation. Mutations can change the meaning of genes because they typically change the amino acids. Signup and view all the answers

Define emerging viruses and give several examples

Emerging Virus: A virus that has appeared suddenly or has recently come to the attention of medical scientists. Examples: HIV, H1N1, Ebola, West Nile virus, and SARS. Signup and view all the answers

Describe a bacterial plasmid and explain how it can serve as a carrier for gene transfer

A small DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. An F factor 'fertility' carries info for sex pili and other proteins. Signup and view all the answers

Describe recombinant DNA technology

The process of combining DNA to form two different species in a test tube. Signup and view all the answers

Identify the steps in gene cloning

<ol> <li>Isolate DNA from organism containing desired gene. 2. Attach target gene to small, circular piece of DNA called a plasmid. 3. Put plasmid into the bacteria. 4. Grow the bacteria. 5. Once bacteria population reaches the desired amount, break bacteria apart. 6. Filter mixture of broken bacteria cells and collect only the plasmids with bonds. 7. Put plasmids into human cells. 8. Over time plasmid will be incorporated into host cell DNA and new genes will change the proteins produced. 9. Observe physical changes between cells with plasmid and those without plasmid.</li> </ol> Signup and view all the answers

Explain how enzymes are used to 'cut and paste' DNA

Restriction enzymes cut DNA, a piece of DNA from another source (gene of interest) is cut by the same enzyme and added to the original DNA. Both molecules of DNA are cut unevenly, yielding 'sticky ends'. Complementary ends on two different fragments stick together through base pairing. The temporary union between two DNA molecules becomes permanent through DNA ligase, thus creating new covalent bonds. Signup and view all the answers

Define DNA ligase

An enzyme essential for DNA replication, catalyzes the covalent bonding of adjacent DNA polynucleotide strands. DNA ligase is used in genetic engineering to paste a specific piece of DNA containing a gene of interest into a bacterial plasmid or other vector. Signup and view all the answers

Study Notes

Structure of Nucleotides

Nucleotides are composed of three components: a sugar (deoxyribose), a phosphate group, and one of four nitrogenous bases (Cytosine, Thymine, Adenine, Guanine).

Formation of Polynucleotides

Polynucleotides form through covalent bonds between the phosphate group of one nucleotide and the third carbon atom of the pentose sugar of the next nucleotide.

Nucleotide Variations in DNA

DNA contains four nucleotides: Cytosine, Thymine, Adenine, and Guanine, which differ in their nitrogenous bases.

DNA vs. RNA

DNA has deoxyribose sugar and bases A, T, C, G; RNA has ribose sugar and bases A, U, C, G.

Structure of DNA

DNA molecules have a double-stranded helical structure, resembling a twisted ladder.

DNA Replication and Base Pairing

DNA replication relies on base pairing: Adenine pairs with Thymine, and Cytosine pairs with Guanine, leading to the creation of daughter DNA.

Stages of Protein Synthesis

Protein synthesis consists of two main stages: transcription and translation.

Transcription Process

Transcription involves synthesizing RNA from a DNA template.

Translation Process

Translation synthesizes polypeptides using genetic information encoded in mRNA.

Codons and Amino Acids

Codons are triplet sequences of bases that correspond to specific amino acids, converting genetic information into protein sequences.

Role of mRNA

mRNA carries genetic information from DNA to the cytoplasm, where it is translated into polypeptides.

Function of Transfer RNA (tRNA)

tRNA translates codons in mRNA into corresponding amino acids during protein synthesis.

Ribosomes in Polypeptide Synthesis

Ribosomes consist of two subunits made of proteins and ribosomal RNA, coordinating mRNA and tRNA to facilitate polypeptide synthesis.

Mutagens and Gene Mutation

Mutagens are agents that cause mutations by altering DNA. Mutations can change genes and affect amino acid sequences.

Emerging Viruses

Emerging viruses are newly identified or sudden viruses of interest to scientists, including HIV, H1N1, Ebola, West Nile Virus, and SARS.

Bacterial Plasmids

Plasmids are small, independent DNA molecules in bacteria that can carry genes and facilitate gene transfer, such as the F factor associated with sex pili.

Recombinant DNA Technology

Recombinant DNA technology combines DNA from different species in vitro for various applications.

Steps in Gene Cloning

Key steps in gene cloning include isolating desired DNA, attaching it to a plasmid, introducing it into bacteria, growing the bacterial culture, and eventually integrating it into host cell DNA for observation of changes.

Cutting and Pasting DNA with Enzymes

Restriction enzymes cut DNA at specific sites, creating sticky ends that allow different DNA fragments to join together. DNA ligase then covalently bonds these fragments permanently.

Role of DNA Ligase

DNA ligase is crucial for DNA replication and genetic engineering, facilitating the bonding of adjacent DNA strands and aiding in the integration of new genes into plasmids.

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Description

Test your knowledge of nucleotides and their structures with these flashcards from Biology Unit 8. Each card highlights key concepts relating to the composition and arrangement of nucleotides, helping you understand their role in polynucleotides. Perfect for reviewing important biological concepts!