Dna rtt packet comprehensive (1 3 to start)

DNA – Structure, Replication, Transcription, and Translation: Molecular Biology of the Gene

DNA RNAThe three main parts are…

Shape…

Bases…

Does what…

Found where…

DNA and RNA are polymers of nucleotides

Draw and label a DNA single nucleotide below

Draw and label two DNA nucleotides bound together as a rung of the double helix

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DNA is a double stranded-helix

Look carefully at the orientation of the sugar-phosphate backbones. What do you notice about the direction of the two backbones?

DNA replication depends on specific base pairing.In DNA replication the strands separate and enzymes use each strand as a template to assemble the new complementary strands.

Fig. 10.4A

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DNA replication: A closer lookDNA replication begins at specific cites on the double helix called ___________________, where __________ start the process to replicate DNA. Replication occurs in both directions (see figure below), however replication can only proceed in the __________direction. Because of this there is a ____________strand and a ___________ strand. The enzyme that splits the DNA apart is called __________________.

Why do you think that replication bubbles usually start at bond between adenine – thymine?

There will be a supplemental homework emailed to you which will give you more details about DNA replication and the enzymes involved.

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The flow of genetic information from DNA to RNA to protein

10.2 The DNA genotype is expressed as proteins, which provide the molecular basis for phenotypic traits.

Central Biology Concept: __________________

____________________________________

____________________________________

____________________________________

____________________________________

__________________________________ Figure 10.6A

Check in question: In the information flow from DNA to protein, what are the functions of transcription and translation?

10.3 Genetic information written in codons is translated into amino acid sequences.

On the RNA strand, each bracket contains

____ nucleotides. _____ nucleotides are

called a _______, each codon represents

an amino acid.

There are 64 (43) possible code words which is more than enough to code for the _____amino acids. What does this mean?

Check in question: A particular protein is 100 amino acids long. How many nucleotides make up the gene for this protein?

10.4 The genetic code is the Rosetta stone of life

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STOP

Before we go any further, go back and make sure you get what we have done so far.

Use the codon chart below to answer the following questions.

1. AUG is the start codon. What amino acid does AUG represent and how many start codons are there?

2. How many stop codons are there? What are they?

3. Translate this sequence: CCAUUUACG

4. In a set of twins, there was a mistake copying the section of the chromosome which you just translated. In both situations uracil was replaced by thymine. Dan has the new sequence is CCAUUCACG and Evan has the sequence CCACUUACG. Translate both of the new sequences and compare them to the original sequence in question 3.

Translation of the original sequence __________________Translation of Dan’s sequence __________________Translation of Evan’s sequence __________________

Even though there was only one base change, what happened?

10.5 Transcription produces genetic messages in the form of RNATranscription is the process of transferring the genetic material from _______ to _______, it occurs in the ______________.

Fig. 10.9B

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Elongation

10.6 Eukaryotic RNA is processed before leaving the nucleus

The kind of RNA that encodes the amino acid sequence is called _________________ because it conveys genetic information from DNA to the translation machinery of a cell.

Processing of eukaryotic RNA (Fig 10.10)

In eukaryotes, newly transcribed RNA molecules are processed (modified) to make mature mRNAs. In order to do this a _______ (an extra G) is added at the 5’ end and a _______(multiple A’s) is added at the 3’ end. _______ is the removal of internal noncoding sequences (_________).

Introns vs. Exons

Many eukaryotic genes contain non- coding regions called ___________.

The coding regions are called _______.

Both introns and exons are transcribed. Introns are removed by _________.

Mature mRNA do not contain introns.

Check in question: Explain why many eukaryotic genes are longer than the mRNA that leaves the nucleus.

10.7 Transfer RNA (tRNA) molecules serve as interpreters during translation.A cell that is ready to carry out translation has in its cytoplasm a supply of amino acids, either obtained from food or made from other chemicals. The amino acids themselves cannot recognize the codons in the mRNA. tRNA must perform two tasks:

1.

2.

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tRNA is made up of about 80 nucleotides and consists of several loops. The bottom loop contains the anticodon. The anticodon in this picture is GCG and it attracts the amino acid ARG (Arginine).

Check in question part 1: If a mRNA anticodon is AAA what is the amino acid that it would bind with? ** Use the codon chart on page 5 of the packet to help you **

Check in question part 2: What is an anticodon and what is its function?

10.8 Ribosomes build proteins

In chapter 4 we learned that ribosomes make proteins, much like a factory makes products. Just like a factory has specific areas for production, a ribosome does too.

Ribosomes have a large and a small subunit and two binding sites:

________ – holds tRNA carrying growing polypeptide.

________ – holds tRNA carrying the next amino acid to be added.

Check in question: How does a ribosome function during protein synthesis?

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10.9 An initiation codon marks the start of an mRNA message

Translation can be divided into the same three phases as transcription:

Initiation occurs in two steps (see figure below). Looking at the pictures below, describe (in your own words) what is happening in steps 1 and two.

Check in question: What would happen if a genetic mutation changed a start codon to some other codon?

10.10 Elongation adds amino acids to the polypeptide chain until a stop codon terminates translation.

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1.2.3.

Figure 10.13B

10.11 Review: The flow of genetic information in the cell is DNA RNA Protein

Look back through section 10.6 to 10.14, working alone or with a partner, draw or summarize the flow of genetic information. Be sure to include where transcription and translation happen and the main products. Also, use this time to make note of any concepts you are confused about so that you can ask questions.

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1. Codon recognition

2. Peptide bond formation

3. Translocation

10.12 Mutations can change the meaning of genes.

Viruses: Genes in Packages

10.13 Viral DNA may become part of the host chromosome

There are two types of reproductive cycles for viruses: ___________ and _____________

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Normal Gene mRNA Protein

Base Substitution

Base Deletion

Deletion or insertion of a nucleotide within the coding sequence will result in the shift in the reading frame and will change the amino acid sequence after the mutation. This is also known as __________________________________

______________ – creation of mutation

______________ – agents that induce mutagenesis

Examples: ________________________

Most mutagens are also ____________(cancer causing agents).

Connections 10.18-10.20: Viruses threaten plants, animals and human health.

10.21 HIV is a retrovirus.

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Connections 10.18-10.20: Viruses threaten plants, animals and human health.

10.21 HIV is a retrovirus.

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Connections 10.18-10.20: Viruses threaten plants, animals and human health.

10.21 HIV is a retrovirus.

Modified from Ms. Saxe – Dr Fox’s ABlock

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