Genetics BIO.B.2

Protein Synthesis

RNA Made up of 1.Phosphate 2.Ribose (a sugar) 3.Four bases RNA bases are: ◦Adenine ◦Guanine ◦Cytosine ◦Uracil (instead of thymine)

Single stranded Forms part of ribosomes Two types of RNA: ◦tRNA (transfer) ◦mRNA (messenger)

TRANSCRIPTION USING DNA TO MAKE mRNA RNA polymerase (an enzyme) unzips DNA by breaking the Hydrogen bonds between the bases.

Only one strand of DNA is transcribed. Complementary RNA nucleotides are added to the DNA strand. DNA RNA  A – U  G – C  T – A  C – G

The start codon is the signal for the place to start transcription. Transcription stops at the stop codons. The sequence of bases along DNA that is transcribed is a gene. The RNA that is made is mRNA. DNALC animation

mRNA PROCESSING After mRNA is made, enzymes may cut out pieces of the strand. The sections that are removed are called introns.

The sections that remain are called exons and are put together. The finished/mature mRNA strand then leaves the nucleus and is ready for translation.

The Importance of Proteins Each gene controls the making of a protein. A gene is section of DNA that gives instructions for a specific protein to be made

20 amino acids make up all proteins Proteins are required for almost every reaction that occurs in your body!

CODONS Codon - three bases in a row that determine the amino acid that is used to make a protein.

mRNA Codon Chart

Some codons do not represent amino acids, but instead act as stop signals (the end of a protein). Note, one amino acid may have more than one codon.

TRANSLATION FROM mRNA TO PROTEIN Begins when a ribosome attaches to a mRNA strand. mRNA is used to make a specific protein (or polypeptide).

RIBOSOMES The organelle where proteins are made. They are made up of 2 subunits with 2 binding sites.

tRNA tRNA (transfer RNA) is a strand of nucleotides that has an amino acid attached to it. tRNA carries the appropriate amino acid to the mRNA/ribosome complex. If mRNA is UGG then the tRNA is ACC.

Translation begins with the start codon. Each amino acid that is brought in to the ribosome is attached to the growing amino acid chain (or protein) The bond between amino acids is called a peptide bond.

About 15 amino acids are added per second. Translation stops when a stop codon is reached. There are no tRNA’s for the stop codons. The protein is released to do its job.

Where does the protein go? Sometimes the finished protein goes into the rough ER. The rough ER transports it to various places including the plasma membrane, Golgi apparatus, and cytoplasm. The Golgi processes and packages proteins. Fro example, some proteins have sugars attached to them. The remodeled proteins leave the Golgi in vesicles (sacs) to go to other parts of the cell or to leave the cell.

BIOTECHNOLOGY The future is here!

MUTATIONS ◦Mutation - changes in the DNA sequence that affect genetic information ◦Types of mutations:  Gene mutations - changes within a single gene  Chromosomal mutations - changes within a whole chromosome (affects multiple genes)

Gene Mutations Point Mutation - a change in a single nucleotide (example: changing an A to a C) Frame-shift Mutation - an insertion or deletion of a nucleotide that causes a different reading of codons from the point of the change to the end of the gene

Point Mutations Normal AAT TAA TAG GAT TTT AAA Mutation AAT TAG TAG GAT TTT AAA  The G was used instead of an A.

Frame-Shift Mutations Usually occurs as a result of an insertion or deletion Normal TAC GCA TGG ATT Insertion TAT CGC ATG GAT T  T was inserted after the A.

Example using words: THE FAT CAT ATE THE RAT TEF ATC ATA TET HER AT not make sense, frameshift Just like this mutated sentence does mutations make nonsense proteins that cannot do their jobs correctly.  DELETION of H

Chromosomal Mutations Deletion – when part or all of a chromosome is lost Duplication – when part of a chromosome is mistakenly repeated Inversion – when part of a chromosome becomes oriented in reverse of its normal direction Translocation – when one part of a chromosome breaks off and attaches to another nonhomologous (not the partner) chromosome

Chromosomal Mutations  Deletion  Duplication  Inversion  Translocation

When do mutations occur? During DNA replication, mistakes can be made when DNA polymerase adds complementary nucleotides. If this mutation or mistake happens very early on in a baby’s development, the mutation can affect the entire baby. The rest of the cells will have that same mutation. Remember, we all start off as one cell that must make many news cells through mitosis. Every time your cells divide, DNA has to copy itself and mistakes can be made.

If a one of your skin cells divides right now and a mutation occurs, this is probably not a problem. However, if the mutation causes certain genes to change, the new, mutated skin cell can become a cancer cell.

Cause of mutations Mutagen – any agent that causes DNA to mutate ◦UV light ◦Radiation ◦Smoking ◦Many different chemicals Mutations gone wild CatsCats

Gene Regulation Only some of your genes are being expressed (used to make protein) at any given time. Your body needs mechanisms to “turn on” or “turn off” genes. Chemicals can act as blocks or starters. Some cancers are caused by genes being turned on that should not have been! For example, these genes can be turned on by smoking, which mutates DNA.

Genetic Engineering Manipulating DNA

Electrophoresis DNA is cut by restriction enzymes to make fragments. ◦Restriction enzymes cut DNA at specific sequences. Electrophoresis is a technique that separates DNA fragments (using electricity) in a jello-like slab based on the size of the fragments. Smaller fragments are able to travel longer distances more quickly. DNA has a negative charge so the fragments will flow toward the positive electrode (opposites attract).

 DNA plus restriction enzyme  Mixture of DNA fragments  Ge l  Powe r source

If you were to compare two samples of the same DNA using the same restriction enzymes, the banding pattern would be the same. Different people make different banding patterns.

And why would we do this? DNA Fingerprinting ◦Paternity Tests  Children have a banding that is a combination of their mom’s and dad’s banding. ◦Crime solving  Identify the person who committed a crime (no two people have the same DNA) ◦Medical diagnosis  Determine if you have the gene that causes a disease or disorder.

GMOs Genetically modified organism (GMO) – an organism with DNA that has been altered through genetic engineering Transgenic - a GMO that has been altered with DNA from another species

Transgenic Bacteria Bacteria have had many different genes put into them ◦Some examples of human genes that are put into bacteria  Insulin gene  Human growth hormone gene  Clotting factors gene

Transgenic Animals Used to study genes and improve the food supply ◦Mice with human-like immune system genes. ◦Livestock with extra copies of growth hormone genes. ◦Sheep and pigs that produce human proteins in their milk.

Transgenic Plants Used for food supply and medical supplies ◦Rice with Vitamin A (beta- carotene) gene ◦Genes for herbicide and pesticide resistance in plants

Cloning Producing genetically identical organisms from one original cell. We have successfully cloned pigs, cows, mice, sheep, and monkeys. The first animal cloned was a sheep named Dolly in 1997.

 A donor cell is taken from a sheep’s udder.  Donor Nucleus  The fused cell begins dividing normally.  Embryo  The embryo is placed in the uterus of a foster mother.  Foster Mother  The embryo develops normally into a lamb— Dolly  Cloned Lamb  Egg Cell  An egg cell is taken from an adult female sheep.  The nucleus of the egg cell is removed.  These two cells are fused using an electric shock.  Fused Cell

GENETICS

Genetics – the study of heredity or passing on of genes Gene – a sections of DNA that codes for a protein to be made Allele – the form that a gene takes (ex. dominant or recessive) Homozygous – having the same alleles for a trait

Heterozygous – having different alleles for a trait Dominant trait – an allele that is fully expressed in heterozygotes; represented by a capital letter Recessive trait – an allele that is not observed in heterozygotes; represented by a lower case letter Genotype – the combination of alleles (letters) that an organism has Phenotype – the physical trait or visible characteristic determined by the genes

Link between meiosis and genetics: Link between meiosis and genetics:

Single Trait Crosses: Single Trait Crosses:

Pedigree :

Incomplete Dominance Crosses:

Codominance Crosses:

Multiple alleles crosses:

Blood Types BLOOD TYPES GENOTYPES ANTIGENS (MARKERS) ANTI-BODIES (FIGHTERS) RECEIVE FROM? DONATE TO? TYPE A TYPE B TYPE AB TYPE O

Blood Type Crosses:

Sex-linked Crosses: