Biology Review

Macromolecules, DNA, Phases, Translation/Transcription.

Protein

An organic compound that is made of one or more chains of amino acids and that is a principal component of all cells

Protein Synthesis

the formation of proteins by using information contained in DNA and carried by mRNA

Transcription

synthesis of an RNA molecule from a DNA template

Translation

Process by which mRNA is decoded and a protein is produced

mRNA

messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome

tRNA

transfer RNA; type of RNA that carries amino acids to the ribosome

Ribosome

site of protein synthesis

mRNA codon chart

helps you find the amino acid from mRNA codons

mRNA codon AUG

the amino acid methionine (Met)

mRNA codon CCC

proline

silent mutation

A mutation that changes a single nucleotide, but does not change the amino acid created.

missense mutation

A base-pair substitution that results in a codon that codes for a different amino acid.

nonsense mutation

A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.

insertion mutation

the addition of one or more nucleotide base pairs into a DNA sequence

deletion mutation

a mutation in which one or more pairs of nucleotides are removed from a gene

frameshift mutation

mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide

DNA Helicase

This is the enzyme that unwinds the double helix and breaks hydrogen bonds to form a replication bubble.

Topoisomerase

This enzyme travels in front of DNA Helicase to relieve the tension on the rest of the double helix by breaking sugar-phosphate bonds. These bonds will be re-formed when replication is complete.

Single Stranded Binding Proteins

These molecules bind to the template strands near the replication fork to keep the hydrogen bonds from reforming (they keep each side of DNA single stranded in order for a newly synthesized complement to be made).

RNA Primase

Primary = first or start;

DNA Polymerase III

This is the first building enzyme. It will build the complement strand of DNA, starting at the RNA primers. The downside of this enzyme is that it can only read in the 3' to 5' direction (and build in the 5' to 3' direction) -- which means only one enzyme is needed for the leading strand, but multiple enzymes will be required for the lagging strand.

Nucleoside Triphosphates

These are the molecules that will be the nucleotides that make up the newly synthesized complement strand. These have two extra phosphates, both of which will be broken off to provide energy for the process of building the complement strand.

Leading Strand

This is the newly synthesized DNA strand that is built in the same direction as the replication fork (DNA is read in the 3' to 5' direction -- so this strand is built by reading that template strand). This strand is built continuously in one long segment & requires only one primer (as well as one DNA polymerase III, one DNA polymerase I, and one DNA ligase). This is the side that is not a pain. :)

Lagging Strand

This is the side that is more work to build. It is built in the opposite direction of the replication fork. Because DNA strands are antiparallel, it is built along the 5' to 3' side. DNA polymerase can ONLY work by reading in the 3' to 5' direction, so this strand has multiple primers and is built in small sections (Okazaki fragments).

DNA Polymerase I

Once the RNA primers have done their job, they need to be replace with DNA nucleotides. This enzyme that removes RNA primers and replaces them with DNA nucleotides. This enzyme is used MANY times on the lagging strand because there are lots of primers, but only once on the leading strand.

DNA Ligase

This enzyme joins unattached sections of DNA by forming bonds between the sugars and phosphates of different nucleotides. It also attaches the Okazaki fragments of the lagging strand together. Like other enzymes, this is used only once on the leading strand, but MANY times on the lagging strand.

Exonucleases

These are built in repair mechanisms that help proof-read the new strand for errors, and remove and correct any mismatches.

DNA

deoxyribonucleic acid, a self-replicating material present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information.

DNA Structure

DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine

DNA "backbone"

Made of deoxyribose sugars and phosphate groups

Nitrogen bases in DNA

Adenine, Thymine, Guanine, Cytosine

Base Pair Rule in DNA

A-T

G-C

A-T

Nitrogen bases held together with

hydrogen bonds

DNA is __________________ stranded

double

RNA is _________________ stranded

single

RNA does not contain

Thymine

RNA bases

A, U, C, G

In RNA, ______________ replaces thymine.

Uracil

Nucleotide

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

Sugar in DNA

deoxyribose

Sugar in RNA

ribose

Self-replicating nucleic acid

DNA

Mitosis

part of eukaryotic cell division during which the cell nucleus divides

Meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

Produces 2 identical somatic cells

Mitosis

Produces 4 genetically different haploid cells

Meiosis

Crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

diploid

(genetics) an organism or cell having two sets of chromosomes or twice the haploid number

haploid

(genetics) an organism or cell having only one complete set of chromosomes

somatic cell

any cell of a living organism other than the reproductive cells.

gamete

sex cell

Meiosis I

separates homologous chromosomes

Meiosis II

the second phase of meiosis consisting of chromatids separating to produce haploid cells

independent assortment

One of Mendel's principles that states that genes for different traits can segregate independently during the formation of gametes

Law of Segregation

Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete

Cell Cycle

series of events that cells go through as they grow and divide

Interphase

Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases

G1 phase

The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.

S phase

The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.

G2 phase

The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.

Mitosis

part of eukaryotic cell division during which the cell nucleus divides

Prophase

Chromosomes become visable, nuclear envelop dissolves, spindle forms

Metaphase

second phase of mitosis, during which the chromosomes line up across the center of the cell

Anaphase

Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell

Telophase

the final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.

Cytokinesis

division of the cytoplasm

chromatin

Substance found in eukaryotic chromosomes that consists of DNA tightly coiled around histones

chromosome

A threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins.

G0 phase

A nondividing state in which a cell has left the cell cycle.

Cancer

disorder in which some of the body's cells lose the ability to control growth

Cyklins

proteins that regulate the cell cycle