BioPsy: Finals L1 - Genetics, Evolution, Development, and Plasticity

Genes

Units of heredity that maintain their structural identity from one generation to another.

Chromosomes

Strands of genes.

Homozygous

Having the same genes on your two copies of some chromosome.

Heterozygous

Having an unmatched pair of genes.

Allele

Alternative forms of a gene; represented by a letter.

Human eye color

Comes in two alleles:

B for brown and b for blue.

Genotype

Reflects the genetic makeup of an individual. Represented as a pair of alleles in letters.

Greek: genos=birth; typos=mark

BB

Homozygous dominant

Bb

Heterozygous dominant

bb

Homozygous recessive (or simply, recessive)

Phenotype

The expressed trait of the individual.

Greek: phainein=to appear; typos=mark

• BB - The human will have brown eyes.

• Bb - The human will have brown eyes.

• bb - The human will have blue eyes.

Dominant Gene

Shows a strong effect in either the homozygous or heterozygous condition.

Recessive Gene

Shows its effect only in homozygous condition.

Gregor Johann Mendel

• His experiments showed that the inheritance of certain traits in pea plants follows patterns, subsequently becoming the foundation of modern genetics and leading to the study of heredity.

• The father of Modern Genetics

Punnet Square

Helps us predict certain outcomes of traits in an organism.

Reginald Punnet and William Baterson.

Creators of the Punnet Square.

Deoxyribonucleic acid (DNA)

• Long-term storage of genetic information; transmission of genetic information to make other cells and new organisms.

• The hereditary material of an organism; it contains the codes for our physical traits such as eye color, hair color, etc.

Nucleus

DNA is tightly packed into chromosomes, which are located inside our cell’s _______.

Ribonucleic Acid (RNA)

• Used to transfer the genetic code from the nucleus to the ribosomes to make proteins.

• Used to transmit genetic information in some organisms and may have been the molecule used to store blueprints in primitive organisms.

Structural Features: DNA

• B-form double helix

• A double-stranded molecule consisting of a long chain of nucleotides.

Structural Features: RNA

• A-form helix

• Usually a single-strand helix consisting of shorter chain of nucleotides.

Propagation: DNA

Is self propagating.

Propagation: RNA

Is synthesized from DNA on an as-needed basis.

Base Pairing: DNA

• AT (Adenine-Thymine)

• GC (Guanine-Cytosine)

Base Pairing: RNA

• AU (Adenine-Uracil)

• GC (Guanine-Cytosine)

Sex Linkage

A special mode of inheritance influenced by sex chromosomes.

Sex-linked

The trait is carried in either X or Y chromosome.

Ex. Color-blindness

Sex-influenced

The heterozygous genotype’s phenotype is influenced by the sex of the individual.

Ex. Baldness

Sex-limited

The trait is carried only by either male or female, but not both.

Ex. Lactation (possible only in females.)

Evolution

A change over generations in the frequencies of various genes in a population.

Evolutionary Psychology

Concerns how behaviors evolved. The emphasis is on evolutionary and functional explanations— that is, how our genes reflect those of our ancestors and why natural selection might have favored the genes that promote certain behaviors.

Altruistic Behavior

An action that benefits someone other than the actor. A gene that encourages altruistic behavior would help other individuals survive and spread their genes, at a possible cost to the altruistic individual.

Kin Selection

Selection for a gene that benefits the individual’s relatives. A gene spreads if it causes you to take great efforts, even risking your life, to protect your children.

Homeobox Genes

Found in vertebrates, insects, plants, even fungi and yeast – regulate the expression of other genes and control the start of anatomical development.

Stage 1: Brain at 3 Weeks

Stage 2: Brain at 7 Weeks

Stage 3: Brain at 11 Weeks

Stage 4: Brain at Birth

Proliferation

The production of new cells. Early in development, the cells lining the ventricles of the brain divide. Some cells remain where they are as stem cells, continuing to divide, whereas others migrate of the migration occurs before birth.

Synaptogenesis

The formation of synapses, begin long before birth, but it continues throughout life, as neurons form a new synapses and discard old ones. The process generally slows in older people, as does the formation of new dendritic branches.

Myelination

Slower stage of neuronal development, the process by which glia produce the insulating fatty sheaths that accelerate transmission in many vertebrate axons.

Myelin

Forms first in the spinal cord and then in the hindbrain, midbrain, and forebrain.

Neuroplasticity

Brain’s ability to change and adapt.

Structural Plasticity

Experiences or memories change a brain’s physical structure.

Functional Plasticity

Brain functions move from damaged area to undamaged area.

Possible Causes of Brain Damage

Includes:

• Tumors

• Infections

• Exposure to radiation

• Toxic substances

• Parkinson’s Disease

• Alzheimer’s Disease

Concussion

• A traumatic brain injury that changes the way your brain functions.

• The brain is made up of soft tissue. When the skull is jolted too fast or is impacted by something, the brain shifts and hits against the skull.

• Can lead to bruising and swelling of the brain, tearing the blood vessels and injury to nerves.

• Most are mild and can be treated with appropriate care. But left untreated, it can be deadly.

Cerebrovascular Accident (Stroke)

Temporary interruption of normal blood flow to a brain area.

Ischemia

• The result of a blood clot or other obstruction in an artery.

• The neurons deprived of blood lose much of their oxygen and glucose supplies.

Hemorrhage

• The result of a ruptured artery. Effects of strokes vary from barely noticeable to immediately fatal.

• They are flooded with blood and excess oxygen, calcium and other chemicals.

Thrombotic Strokes

Are caused when a blood clot forms in an artery leading to the brain.

Intracerebral Hemorrhage

A weak blood vessel breaking inside the brain.

Embolic Strokes

Begin with a clot forming elsewhere in the body — such as the heart or neck — that breaks loose and travels to the brain.

Subarachnoid Hemorrhage

A weak blood vessel breaking on the surface of the brain

Edema

Increases pressure on the brain and the probability of additional strokes.

Edema and Sodium

The combination of _____ and excess _____ provokes excess release of the transmitter glutamate which overstimulate neurons, damaging both the neurons and synapses.