second sem | gen bio ii

genetics, pedigree chart, origin & characteristics of life | terms only

Gregor Mendel

Gregor Mendel

Austrian monk responsible for the laws governing inheritance of traits; developed laws of inheritance while studying the traits in pea plants

particulate inheritance

Mendel stated that physical traits are inherited as “particles” (were actually chromosomes & DNA)

trait

any characteristic that can be passed from parent to offspring

heredity

passing of traits from parent to offspring

genetics

the study of heredity

monohybrid cross

cross involving a single trait like flower color

dihybrid cross

cross involving two traits like flower color & plant height

punnett square

used to help solve genetics problems

alleles

two forms of a gene (either dominant or recessive)

dominant

stronger of two genes expressed in the hybrid; represented by a capital letter

recessive

gene that shows up less often in a cross; represented by a lowercase letter

genotype

gene combination for a trait (e.g. RR, Rr, rr)

phenotype

the physical feature resulting from a genotype (e.g. red, white)

homozygous genotype

gene combination involving 2 dominant (RR) or 2 recessive (rr) genes; also called “pure”

heterozygous genotype

gene combination of one dominant & one recessive allele (Rr); also called hybrid

pisum sativum

scientific name for peas

self-fertilization

fertilization that can occur in the same flower

cross-fertilization

fertilization can occur between flowers

parental (P1) generation

the parental generation in a breeding experiment

F1 generation

the first-generation offspring in a breeding experiment; from breeding individuals from the P1 generation

F2 generation

the second-generation offspring in a breeding experiment; from breeding individuals from the F1 generation

law of dominance

In a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation; all the offspring will be heterozygous and express only the dominant trait

law of segregation

During the formation of gametes (eggs or sperm), the two alleles responsible for a trait separate from each other. Alleles for a trait are then "recombined" at fertilization, producing the genotype for the traits of the offspring.

law of independent assortment

Alleles for different traits are distributed to sex cells (& offspring) independently of one another (This law can be illustrated using dihybrid crosses.)

incomplete dominance

both alleles of a gene are partially expressed in an intermediate phenotype

codominance

both alleles of a gene are distinctly expressed

sex-linked traits

traits (genes) located on the sex chromosomes (i.e. X and Y)

pedigree chart

show a record of the family of an individual to trace a genetic trait or disease over several generations; can be used to study the transmission of a hereditary condition

(1) made up of cells (2) reproduce (3) obtain and use energy (4) homeostasis (5) hereditary (6) responsiveness (7) growth & development (8) adaptation

8 characteristics of life

cells

smallest unit capable of all life functions

unicellular organism

entire organism is one single cell (e.g. bacteria & protozoa)

multicellular organism

organism is made up of many cells that each have specialized functions within the organism

reproduction

the process of producing new organisms of the same type

asexual reproduction

a single parent organism reproducing by itself

sexual reproduction

two different parent organisms contribute genetic information; involves the combination of male & female sex cells

energy

needed for growth, development, damage repair, and reproduction

anabolism

process of building up complex substances from simpler substances (e.g. photosynthesis)

catabolism

breaking down complex substances to simpler substances (e.g. digestion & cellular respiration)

metabolism

total of all chemical reactions in an organism

homeostasis

a stable state of conditions in the body that are necessary for life (e.g. body temperature, blood pressure, pH and water balance)

genes

carry hereditary information; composed of DNA

mutations

changes DNA code and can be passed down from generation to generation

responsiveness

organisms react to various stimuli like light, temperature, odor, sound, gravity, heat, water, and pressure

growth

to get bigger in size

development

involves a change in the physical and physiological change makeup of an organism

adaptation

process of that enables organisms to become better suited to their environment

evolution

species obtain adaptations through _______ over great periods of time

extraterrestrial origin

life originated on another planet outside our solar system

panspermia

“seed” of life exists all over the universe and can be propagated through space, and that life on Earth originated from those seeds

divine creation

Life was put on Earth by divine forces. Creation theories are common to many of the world’s religious and cultures

origin from nonliving matter

Life arose on Earth from inanimate matter after Earth had cooled. Random events probably produced stable molecules that could self-replicate.

Aristotle

proposed the theory of abiogenesis

abiogenesis

idea that living things can arise from nonliving matter (“pneuma”)

spontaneous generation

the formation of living organisms without arising from a similar organism

Lazzaro Spallanzani

boiled soups for almost an hour and sealed containers by melting the slender necks closed; critics said sealed vials did not allow enough air for organisms to survive and that prolonged heated destroyed life force

Francesco Redi

an Italian physician who did an experiment with flies and wide-mouth jars containing meat, hypothesizing that rotten meat does not turn into flies; results disproved the idea of spontaneous generation for larger organisms but people still though microscopic organisms like algae or bacteria could arise that way

John Needham

showed that microorganisms flourished in various soups that have been exposed to the air; claimed that there was a “life force” present in the molecules of all inorganic matter, including air and the oxygen in it, that could cause spontaneous generation to occur; seemed to support spontaneous generation but people didn’t realize that bacteria were already present in his soups

Anton van Leeuwenhoek

began making and looking through simple microscopes which he used (along with a a magnifying glass) to examine water and visualized tiny animals, fungi, algae and single celled protozoa, which he collectively called “animalcules”

microbes

By the end of the 19th century, animalcules were called _______.

Louis Pasteur

received a prize from the Paris Academy of Sciences when he published the results of an experiment he did to disprove spontaneous generation in microscopic organisms; his experiment had him put broth into several special S-shaped flasks that trapped any dust particles containing bacteria; he found that the S-shaped flask kept microbes out but let air in which proved microbes only come from other microbes

primordial soup theory

theory by Alexander Oparin that states that possible conditions on the primitive Earth allowed the onset of chemical reaction that led to the formation of other complex organic compounds using simple inorganic compounds

Miller-Urey experiment

A mixture of methane, ammonia, hydrogen, and water vapor, to simulate the version of Earth's primitive, reducing atmosphere proposed by Oparin, was introduced into a 5-liter flask and energized by an electrical discharge apparatus to represent ultraviolet radiation from the Sun

The Clay Hypothesis

proposed in 1985 by Graham Cairns-Smith; The first molecules of life might have met on clay, whose surface not only concentrated these organic compounds together but also helped organize them into patterns

Deep Hot Biosphere Hypothesis

Postulated by Thomas Gold; suggests that life did not begin on the surface of the earth but instead in the porosity of it crust