Genetics Ch. 1 & 2

Who created the Theory of Epigenesis?

William Harvey

Epigenesis

the process where a complex organism develops gradually from a simple egg or seed (structures such as body organs), are not initially present in the early embryo and are formed later

Theory of Preformation

The fertilized egg contains a complete miniature adult called homunculus

Who created the cell theory

Schleiden and Schwann (1830)

The cell theory

all organisms are composed of basic structural units called cells

Natural Selection

the mechanism for evolutionary change

Darwin

Published his ideas on the theory of evolution in The Origin of Species

Wallace

Independently proposed the theory of evolution

Mendel

Published his findings in 1866, worked with peas and used quantitative data to support his ideas, believed traits are passed from generation to generation, transmission of genetic information from parents to offspring

Diploid

a cell or organism with two complete sets of chromosomes, one set inherited from each parent, forming homologous pair

Haploid

a cell or organism that has a single set of unpaired chromosomes

Homologous chromosomes

matched pairs of chromosomes in a diploid organism, one inherited from each parent, similar in length

Chromosomal theory of inheritance

inherited traits are controlled by genes residing on chromosomes, genes are transmitted through gametes (maintains genetic continuity from generation to generation)

Sutton and Boveri

proposed that genes are carried on chromosomes

Allele

Mutations produce alleles of a gene, the source of genetic variation

Phenotype

Expression of the genotype, produces an observable trait or phenotype

Genotype

The set of alleles for a given trait

Avery, MacLeod, and McCarty

Published experiments in 1944 that showed DNA was carrier of genetic information in bacteria

Who is the carrier of genetic information?

DNA

Central Dogma

describes the fundamental flow of genetic information in cells: from DNA to RNA, and then from RNA to protein, summarized as DNA to RNA to Protein

Enzymes

biological catalysts (mostly proteins, sometimes RNA), that speed up essential DNA/RNA processes like replication, repair, transcription, and modification

restriction enzymes

“molecular scissors” from bacteria that cut DNA at specific, short sequences, allowed the advent of recombinant DNA and cloning

Genome

an organisms complete set of DNA, containing all the genetic instructions needed to build, operate and maintain it

Vector

a DNA molecule used as a vehicle to carry foreign genetic material (like a specific gene) into another cell, where it can be replicated, expressed, or analyzed, acting as a crucial tool for gene cloning, therapy, and genetic engineering

Recombinant DNA technology

the ability to transfer genes across species

Genomics

studies the structure, function, and evolution of genes and genomes

proteomics

Identifies a set of proteins present in cells under a given condition, studies their functions and interactions

Bioinformatics

Uses hardware and software for processing nucleotide and protein data

Classical/Forward genetics

Identifying the genes that caused mutant phenotypes

Reverse genetics

DNA sequence of a particular gene of interest (GOI) is known, but its function is not

Gene Knockout

allows scientists to render genes nonfunctional to investigate the possible role of that gene

What makes a good model organisms?

Easy to grow, short life cycle, produce many offspring, genetic analysis is straightforward

What are some examples of good model organisms?

E. coli, S. cerevisiae, D. melanogaster, C. elegans, D.rerio, M. musculus

Biotechnology

Used for the genetic modification of crop plants for increased herbicide, insect, and viral resistance, nutritional enhancement, and water use reduction

Watson and Crick

discovered the double-helix structure of DNA in 1953 and have won numerous Nobel Prizes and awards

Eukaryote

have a membrane-bound nucleus and organelles (like mitochondria, ER, golgi), make them larger and more complex

Prokaryote

Don’t have a nucleus, keeping their DNA free in the cytoplasm (nucleoid region) and are generally smaller and simpler

Centromere

constricted regions on chromosomes

q arm

long arm

p arm

short arm

metacentric (centromere)

middle

submetacentric (centromere)

between middle and end

acrocentric (centromere)

close to end

telocentric (centromere)

at the end

somatic cells

body cells, have homologous pairs of chromosomes

karotype

an individual’s complete set of chromosomes, organized by size, shape, and number

mitosis

Partitions chromosomes into dividing cells, produces two daughter cells with full diploid complement of chromosomes

karyokinesis

genetic material partitioned to daughter cells during nuclear division

cytokinesis

cytoplasmic division follows after karyokinesis

cell cycle

composed of interphase and mitosis

interphase

characterized by the absence of visible chromosomes

prophase

centrioles divide, move, establish poles, nuclear envelope breaks down, and chromosomes condense and become visible

sister chromatids

two parts of each chromosomes, connected at the centromere, held together by multi-subunit protein complex called cohesin

metaphase

chromosome configuration following migration, centromeres align on metaphase plate

kinetochore

proteins associated with centromere, spindle fibers bind to kinetochore; chromosomes migrate

cohesin

protein complex that holds sister chromatids together

separase

enzyme that degrades cohesin

shugoshin

protein that protects cohesin from being degraded by separase

anaphase

sister chromatids separate now called daughter chromosomes, migrate to opposite poles by shortening spindle fibers, motor proteins or molecular motors use ATP

disjunction

the normal, essential process where homologous chromosomes or sister chromatids separate and move to opposite poles of a cell during cell division

telophase

uncoiling of chromosomes, re-formation of the nuclear envelope, spindle fibers disappear and nuclear envelope reforms

cell plate

a temporary structure that forms in the middle of a dividing plant cell during cytokinesis

cell furrow

a pinching indentation in the surface of a dividing animal cell that forms during cytokinesis

Cyclins

a family of proteins that act as crucial regulators of the cells cycle, controlling when a cell divides by activating specific enzymes

kinases

an enzyme that catalyzes the transfer of a phosphate group from ATP to a specified molecule

meiosis

leads to production of sex cells, reduces genetic material by half

meiosis I

reductional division, each have prophase, metaphase, anaphase, and telophase stages

meiosis II

equational division

prophase I

homologous chromosomes pair up, condense, and exchange genetic material through crossing over, forming unique recombinant chromosomes while the nuclear envelope breaks down and the spindle fibers begin to form

metaphase I

chromosomes at maximum shortness, terminal chiasmata holding nonsister chromatids together, binding spindle fibers moves chromatids to metaphase plate

Anaphase I

cohesin is degraded between sister chromatids, homologous chromosomes separate and move toward the poles, nondisjunction may occur

Telophase I

cytokinesis, two haploid cells result, nuclear membranes forms, nuclei enter interphase

prophase II

Each dyad is composed of one pair of sister chromatids attached by the common centromeric region

metaphase II

the centromeres are positioned on the equatorial plate

anaphase II

sister chromatids separate, migrate to opposite poles, each haploid daughter cell from meiosis II has one member of each pair of homologous chromosomes

Telophase II

one member of each pair of homologous chromosomes present at each pole, each chromosome is now a monad, cytokinesis results in 4 haploid cells

sister chromatids

two parts of each chromosome, connected at the centromere, held together by multi-subunit protein complex called cohesin

crossing over

exchange of genetic material between homologous, nonsister chromatids. Meiosis significantly increases the level of genetic variation due to crossing over

S phase

DNA is synthesized (the biological process of creating new DNA strands from an existing one)

Bivalent

the paired structure of two homologous chromosomes (one from each parent) during prophase I of meiosis

tetrad

a group of four chromosomes that form during prophase I of meiosis

oogenesis

the biological process of producing female gametes (egg cells or ova) in the ovaries

spermatogenesis

the biological process where immature male germ cells (spermatogonia) develop into mature, motile spermatozoa (sperm) within the testes, involving mitotic and meiotic cell divisions to produce four haploid sperm from a single starting cell, culminating in a transformation (spermiogenesis) into functional sperm