unit 8 making proteins

Point Mutation

(one base in DNA is substituted for another; example - TAT becomes TCT) If a point mutation changes the amino acid, it's called a MISSENSE mutation. If a point mutation does not change the amino acid, it's called a SILENT mutation. If a point mutation changes the amino acid to a "stop," it's called a NONSENSE mutation.

two main types of mutations

- Point Mutation and - Frameshift Mutation

describe the process of transcription in 4-6 steps.

1. RNA polymerase "unzips" the DNA between nitrogen bases 2. A complimentary mRNA strand is formed by attaching complimentary base pairs to one of the DNA strands. 3. Once the genetic code is copied (transcribed) the DNA "zips" back up. 4. mRNA leaves the nucleus through a nuclear pore and takes the message to the cytoplasm

describe the process of translation in 4-6 steps.

1. The ribosome attaches to the mRNA strand and begins reading (translating) the codons until the AUG codon is found. 2. A tRNA molecule with the complimentary bases (anticodon AUG = UAC) carries and amino acid that matches the codon and bonds to the nitrogen bases of the codon in mRNA. 3. The ribosome moves to the next codon, tRNA brings the amino acid coded for in the mRNA sequence and attaches to the mRNA strand. 4. A peptide bond forms between the amino acids through a dehydration synthesis reaction, joining the amino acids. 5. The first tRNA molecule is released and goes back to the cytoplasm to pick up another amino acid. 6. The process continues until a STOP codon is reached and the protein is sent out into the cell for whatever function is coded for in the DNA.

define and explain the term gene.

A gene is a section of DNA that contains the genetic information that codes for specific proteins that ultimately determine an organism's characteristics or traits (ex: eye color, hair color, formation of enzymes, etc).

define the term mutation.

A mutation is change in the nucleotide-base sequence in a DNA molecule during replication

explain how gene expression is regulated

A strand of DNA does not just contain genes. It also has a number of regulatory elements that help control gene expression. Some regulators help turn genes on, causing genes to be expressed. Certain proteins can make it easier for transcription to occur. These proteins help to increase gene expression. Certain sections of DNA mark where a gene begins and ends. This helps the process of transcription occur in the correct area of DNA. Sections of DNA or proteins can turn genes off, or prevent gene expression. Cells typically produce a specific protein only when it is needed. Some genes are housekeeping genes that are always turned on. These genes code for proteins that are always needed.

describe the components that make up the genetic code contained in all living things.

All living things, regardless of whether they contain their genetic material within a nucleus (eukaryotic) or not (prokaryotic) store the genetic code within a type of biomolecule called a nucleic acid, specifically DNA. The sequence of nitrogen bases within the DNA contain the genetic instructions for the individual organism.

explain how the expression of certain genes is a regulated process using the following scenario: Many babies are born with light-colored hair. As they grow and become older, their hair color naturally becomes darker and will eventually become gray.

Gene expression can vary according to age. Genes that control hair color can be ignored or turned off at different life stages, which can result in different hair colors during childhood, adulthood and up to old age

explain how genes are expressed.

Genes are expressed through transcription and translation that code for specific proteins.

explain the purpose of protein synthesis.

Proteins are some of the most valuable molecules for life. Proteins are essential to build muscle, they are found in cell membranes to help with transport, they are enzymes and hormones. Without these biomolecules life would not exist. DNA contains the information needed to produce proteins, so this information must be recorded and read to form these essential molecules

describe the complementary base pairing rules in DNA.

The complementary base pairing rules in DNA state that adenine (A) always pairs with thymine (T) while cytosine (C) always pairs with guanine (G).

describe the complementary base pairing rules in RNA.

The complementary base pairing rules in RNA state that adenine (A) always pairs with uracil (U) while cytosine (C) always pairs with guanine (G). During transcription, if the DNA strand contains thymine (T), then the complementary base in RNA is adenine (A). If the DNA strand contains adenine (A), then the complimentary base in RNA is uracil (U).

identify the section of DNA that contains the genetic code.

The sequence of the nitrogen bases contains the genetic code in DNA.

identify the nucleotides in DNA.

There are four possible nucleotides in DNA. They differ in their nitrogen bases, which are adenine (A), thymine (T), cytosine (C) and guanine (G).

identify the nucleotides in RNA.

There are four possible nucleotides in RNA. They are differ in their nitrogen bases, which are adenine (A), uracil (U), cytosine (C) and guanine (G).

identify where transcription occurs

Transcription occurs in the nucleus

identify where translation occurs.

Translation occurs on ribosomes

Frameshift Mutation

alters the reading frame of the DNA, changing the amino acid sequence; example - TATTCG → TATCTCG) If a base is removed or lost is called a DELETION If an extra base is added it is called an INSERTION