DNA/Genetics

heterozygous

Aa

RNA

a single stand of nucleic acids. It contains 4 bases

RNA 4 bases

- Adenine (A) - Cytosine (C) - Guanine (G) - Uracil (U) A -> U and U -> A C -> G and G -> C

UV light.

- After exposure to UV light adjacent thymine bases in DNA become cross-linked to form a 'thymine dimer'. - This disrupts the normal base pairing and the controlling gene's instructions.

The Genetic Code

- DNA codes for assembly of amino acids. (DNA codes for proteins too) - The code is read in a sequence of three bases which codes for one amino acid

What structure does DNA have

- DNA has a double-helix structure. - If the DNA in a single human cell was unwound, it would be more than two meters long.

What is DNA?

- DNA is called the blueprint for life because it contains all of the information an organism needs to develop, function, and reproduce. - DNA stores and transmits genetic information.

What does DNA look like

- DNA is easily extracted from cells. The cells are disrupted, non-DNA components are removed, and the DNA is precipitated using ethanol. - The DNA extracted from a lot of cells can be made to form a whitish, glue-like material

Purines

- Double-ringed structures - Always pair up with pyrimidines Adenine (A) - DNA & RNA guanine (G) - DNA & RNA

Pyrimidines

- Single ringed structures - Always pair up with purines cytosine (C) - DNA & RNA thymine (T) - DNA only Uracil (U) - RNA only

Types of Mutations

- Some change only one nucleotide base, while others may change large parts of a chromosome. - Bases may be inserted, substituted, or deleted from the DNA.

Trisomy 21

Down syndrome

DNA triplets (IMPORTANT)

Each triplet of DNA codes for one codon. Each codon codes for one amino acid. A protein is a long chain of amino acids * whenever you hear triplet, think DNA triplet->codon->amino acid

Human Female Karyotype

Every cell (except egg cells) in a normal human female has: 44 autosomes (22 pairs) 2 sex chromosomes (1 pair)

Human Male Karyotype

Every cell (except sperm cells) in a normal human male has: 44 autosomes 2 sex chromosomes

alleles

Genes occupying the same position (locus) on homologous chromosomes versions of the same gene that code for a variant of the same polypeptide one individual can only have a maximum of two alleles for a given gene. There may be more than two alleles in a population, e.g blood groups A, B, O. sometimes they are an exacter match between in mom and dad, but sometimes they are different in one gene

Homologous pair of chromosomes

In sexually reproducing organisms, most cells have a homologous pair of chromosomes (one from each parent). In homologous pairs, genes that control the same trait are found at the same locus The egg has one chromosome and the sperm has the other- it makes your pair 2 copies of the same chromosomes, but one is dominant and one is recessive

Mendel's View of Inheritance

Mendel observed that characters could be masked in one generation of peas but could reappear in later generations. He showed that inheritance was particulate in its nature (not blending as was previously thought). We now know these units of inheritance are genes.

Chromosomes

SUPER coiled DNA

Genes

Sections of DNA that code for proteins.

Does the egg or the sperm determine the sex of the baby

Sperm because sperm is X or Y Egg is always X

What kind of shape does a DNA molecule have?

The double-stranded DNA molecule forms a helical shape. The two chains of nucleotides run in opposing directions. Because of this, DNA is said to be antiparallel. The DNA twists because of the charges of molecules

Locus

The position of a gene on a chromosome Humans have the same locus on one chromosome (Ex. Gene for eye color)

Purpose of Meiosis

The purpose of meiosis is to produce haploid sex cells.

Start and stop condons (IMPORTANT)

There are a few codons that make up the START and STOP sequences for polypeptide (protein) chain formation: START: AUG (always methionine aka met) STOP: UAA, UAG, UGA

Phenotype vs. Genotype

What organism looks like vs. homozygous dominant/recessive and heterozygous (appearance vs. allele)

Making proteins

When it's time to make a protein, the DNA code is transcribed into messenger RNA (mRNA) and transported to the ribosome (site of protein synthesis)

Meiosis

a special type of cell division for the purpose of sexual reproduction

Point mutations

affect one base pair in the DNA. The base pair can be lost, duplicated, or substituted

Gregor Mendel

an Austrian monk who is regarded as the father of genetics. Mendel carried out pioneering work using pea plants to study the inheritance patterns of a number of traits (characteristics). Mendel observed that characters could be masked in one generation of peas but could reappear in later generations. What we now call Mendelian genetics is the study of inherited characteristics.

Mutations

are changes to the DNA sequence. Mutations are the ultimate source of new genetic variation (alleles). Mutations occur through errors in DNA copying or as a result of unrepaired damage to DNA from mutagens.

Codes

genes code for the same traits, but they might not be the same (both code for eye color, but one is blue and one is brown)

Is all DNA important

no, some is junk

Histone

proteins organize the DNA into tightly coiled structures (condensed, visible chromosomes) in the first stage of cell division.

Mutagens

substances that can cause a mutation in DNA.

Melanoma

- The development of the ozone-depleted region over Antarctica each year has led to an increase in the mutagenic radiation reaching the Earth's ecosystems. - One of the main diseases caused by this radiation is a form of skin cancer called melanoma. - Melanoma is an aggressive cancer that may be fatal if left untreated. - The cancer spreads from the skin

Non-disjunction in Meiosis

- This mishap is called non-disjunction. - Non-disjunction results in abnormal numbers of chromosomes passing to the gametes. - If either of these aberrant gametes unites with a normal one at fertilization, the offspring will have an abnormal chromosome number. - This is known as an aneuploidy, e.g. trisomy. Egg or sperm has 2 copies of chromosomes (usually egg)

Types of point mutations

- lost - duplicated - substituted The loss or duplication of a base pair causes a reading frame shift as every triplet after the mutation is affected. A substitution may change a single amino acid.

DNA Nucleotides

1. a sugar (deoxyribose) 2. a phosphate group 3. a nitrogen-containing base

RNA Nucleotides

1. a sugar (ribose ) a phosphate group. a nitrogen-containing base

DNA Molecule:

2 "backbones" Double stranded Bases connected to sugar Backbones are connected by hydrogen bonds Bases have pairs

Humans have ____ copy(ies) of each chromosome(s)

2 copies of each

Bases for DNA and RNA

5 Types: 1. Adenine (A) - DNA & RNA 2. guanine (G) - DNA & RNA 3. cytosine (C) - DNA & RNA 4. thymine (T) - DNA only 5. Uracil (U) - RNA only

DNA bases pairs

A pairs with T T pairs with A G pairs with C C pairs with G

Example of an allele gene

Aa: heterozygous BB: homozygous dominant cc: homozygous recessive

Human Karyotypes

All of the chromosomes laid out in a human cell - Display the chromosome contents of a cell, organized according to their number, size and type - Normal somatic human cells have a karyotype with 46 chromosomes (in 23 pairs) comprising: 22 pairs of autosomes. 1 pair of sex chromosomes.These determine the sex of an individual: XX = female XY = male

homozygous

BB: homozygous dominant cc: homozygous recessive

The Bacterial Plasmid

Bacteria commonly contain small circular pieces of DNA called plasmids.

Thymine dimer

Cross linked DNA bases

What do nucleotides make up?

DNA and RNA are made up of many nucleotides

What does DNA stand for

DNA is an acronym for deoxyribonucleic acid.

Where is DNA found?

DNA is found in every cell of all living organisms.

Ionizing Radiation

Mutagenic effects: - Ionizing radiation includes nuclear and ultraviolet radiation, X-rays, and gamma rays. All are potent mutagens. - Ionizing radiation is associated with the development of cancers. Those most at risk: - Those working with radioisotopes. - Those living near nuclear plants, waste dumps, or testing sites. - Fair skinned people in tropical and subtropical regions.

Environmental Poisons

Mutagenic effects: - Many chemicals are mutagenic. - Synthetic and natural examples include: organic solvents (e.g. benzene), asbestos, tobacco tar, vinyl chlorides, and nitrites. Those most at risk: - Chemical industry workers, those in the glue, paint, rubber, resin, and leather industries. - Tobacco smokers. - Coal and other mining workers. - Those regularly exposed to petroleum volatiles and vehicle exhaust emissions.

Viruses & Microorganisms

Mutagenic effects: - Some viruses integrate into the human chromosome, disrupting genes and triggering cancers. Those most at risk: - Those at higher risk of viral infections include intravenous drug users and those with unsafe sex practices

How many forms can mutations come in?

Mutations come in many forms

Nucleotides

Nucleotides are the building blocks of nucleic acids (DNA and RNA).

What structure do Nucleotides have?

Nucleotides have three parts to their structure: - a sugar (deoxyribose in DNA and ribose in RNA). - a phosphate group. - a nitrogen containing base.