Bio Test 8.4/8.5/ 8.6 AJ likes Men

Build proteins

Structure, function, and regulation of the body.

1. DNA Replication

2. Transcription: Converts the DNA into a mRNA (message)

3. Translation: Interprets an RNA message into a string of amino acids, called a polypeptide, which makes up a protein.

Middleman between DNA and protein synthesis.

A chain of nucleotides, each made of a sugar, a phosphate group, and a nitrogen base.

RNA has a ribose sugar.

RNA has uracil instead of thymine. ( A pairs with U)

RNA is a single-stranded structure. (This single stranded structure allows some types of RNA to form complex 3D shapes, and as a result, some RNA molecules can catalyze reactions much as enzymes do.)

Additionally, DNA codes for proteins, while RNA makes proteins.

Nucleus

Copy a sequence of DNA to produce a complementary strand of RNA.

Process of copying a sequence of DNA to produce a complementary strand of RNA.

Enzymes that bond nucleotides together in a chain to make a new RNA molecule.

5'-3' direction

DNA double helix

RNA

mRNA

rRNA

tRNA

Intermediate message that is translated to form a protein.

Forms part of ribosomes, a cell’s protein factories.

Brings amino acids from the cytoplasm to a ribosome to help make the growing protein.

1. INITIATION

2. ELONGATION

3. TERMINATION

Promoter Sequence

Promoter

A segment of DNA that allows a gene to be found and transcribed

Transcribing

A DNA sequence that indicates where a genetic sequence can be read and decoded. It is a type of promoter sequence, which specifies to other molecules where transcription begins.

Using the DNA strand as a template the RNA polymerase makes a complementary strand of RNA.

Elongation is the stage when the RNA strand gets longer, thanks to the addition of new nucleotides.

After a gene has been transcribed, RNA polymerase will encounter a terminator sequence and the RNA strand will be released.

mRNA

Before the mRNA can leave the nucleus and be used it needs to be edited (mRNA splicing).

RNA splicing is a process in molecular biology where a newly-made precursor messenger RNA (pre-mRNA) transcript is transformed into a mature messenger RNA (mRNA). It works by removing all the introns (non-coding regions of RNA) and splicing back together exons (coding regions).

mRNA must be processed before leaving the nucleus.

Exons are nucleotide segments that code for parts of the protein.

Introns are non-coding nucleotide segments that intervene, or occur, between exons.

5' cap tail is added which helps preserve the mRNA and helps ribosomes bind to it.

Poly-A tail is added to help the mRNA leave the nucleus.

Protects mRNA from degradation

Aids in exporting the mature mRNA to the cytoplasm.

Involved in binding proteins to initiate translation.

newly-synthesized mRNA from degradation.

It also assists in ribosome binding to help initiating translation.

The process which translates an mRNA message into a polypeptide chain (protein).

Cytoplasm

Amino acid sequence

Alpha helix, beta sheet and loops

Phi-Psi angle

Arrangement of several Polypeptide chains

20 amino acids

A sequence of 3 nucleotides that codes for an amino acid

Amino acid or function

Amino acids

Signal the end of an amino acid chain.

UAA,UGA, and UAG

Signals the start of translation. AUG which codes for methionine is the start codon.

It's crucial that the mRNA is read correctly.

A misread mRNA could change the protein completely.

Could lead to mutations.

In molecular biology, a reading frame is a way of dividing the sequence of nucleotides in a nucleic acid (DNA or RNA) molecule into a set of consecutive, non-overlapping triplets.

Where these triplets equate to amino acids or stop signals during translation, they are called codons.

The genetic code is shared by almost all living organisms.

Codons are said to be universal throughout all living organisms. This allows crossing species and genetic modification.

The genetic code is universal means the same codons code for the same amino acids in all forms of life that exists today.

The mRNA is read by a ribosomal  subunit (rRNA) and a transfer RNA (tRNA).

The rRNA is composed of 2 subunits a large and small, together they pull the mRNA through reading one codon at a time.

The large subunit holds onto the growing protein chain, while the small subunit holds onto the mRNA.

tRNA carry free-floating amino acids from the cytoplasm to the ribosome.

It's L shaped, (tRNA) one side has an amino acid attached;  the other has a code called the anticodon.

The anticodon is a set of three nucleotides complementary to the mRNA.

mRNA: GGG

tRNA:    CCC (this is the anticodon for GGG)

Large Subunit

Binding sites

Small subunit binds to mRNA

Amino acid

Anti-codon

When dietary protein is in short supply, the body tends to take protein from skeletal muscles to preserve more important tissues and body functions. As a result, lack of protein leads to muscle wasting over time.

The skin might also be affected—proteins enable skin regeneration, and if they do not work adequately, the skin might become dry and cracked.

DNA change

single gene or an entire chromosome.

Mutations can be good, bad, or neither.

The condition when proteins fail to work.

Substitute one nucleotide for another. This means that an incorrect nucleotide is put in the place of the correct nucleotide.

Instead of coding for Glutamic acids, Valine is coded for when making the hemoglobin protein.

Cystic Fibrosis                  Tay-Sachs                Cancer

Silent mutations are mutations in DNA that do not have an observable effect on the organism's phenotype.

A missense mutation is a mistake in the DNA which results in the wrong amino acid being incorporated into a protein because of change, that single DNA sequence change, results in a different amino acid codon which the ribosome recognizes.

A nonsense mutation, or its synonym, a stop mutation, is a change in DNA that causes a protein to terminate or end its translation earlier than expected.

Delete/insert nucleotides that don't belong

Ex. THE CAT ATE THE RAT, delete the first E

THC ATA TET HER AT

Ex. THE CAT ATE THE RAT

Insert an extra C

THE CCA TAT ETH ERA T

Fragile X Syndrome

Huntington's disease

Cri du Chat

Male infertility

Prader Willi syndrome

Changes in structure or number of chromosomes.

One chromosome may have two copies of a gene(s).

A piece of one chromosome moves to a non-homologous chromosome

germ cells during Prophase I of meiosis.

Klinefelter syndrome

XXY syndrome

Affects men only

Down syndrome

Edwards syndrome

Organisms phenotype

silent mutations

to affect an offspring it has to occur in germ cells (gametes).

Agents in the environment that can change DNA.

ndustrial chemicals

They can speed up replication rate or break DNA strands.

Some mutagens occur naturally. Ex. : UV rays from sunlight, pesticides, nicotine, bacteria, viruses, etc...