Biology – Semester 1

cell division

cell reproduction; two "daughter cells" are produced that are genetically identical to each other and to the "parent" cell; replaces damaged or lost cells, permits growth, and allows for reproduction

Chromosomes

tightly coiled strands of long DNA molecules in a cells nucleus that appear when the cell is ready to divide

Asexual Reproduction

single-celled organisms reproduce by dividing in half, and the offspring are genetic replicas of the parent (inherit all of their chromosomes from 1 parent); no fertilization of an egg by a sperm, uses Mitosis

Sexual Reproduction

requires fertilization of an egg by a sperm, use Miosis

Eukaryotic Chromosomes

# it has depends on species; located in the nucleus; made up of chromatin which is composed of DNA which coils around histone proteins to form nucleosomes which interact with one another to form coils and supercoils that make up chromosomes

Sister Chromatids

two copies of a duplicated chromosome containing identical genes

Centromere

Where two sister chromatids are joined together tightly, a narrow "waist"

The Cell Cycle

The ordered sequence of events that extend from the time a cell is first formed from a dividing parent cell to its own division into two cells; Interphase (90%) & Mitotic phase (10%)

Interphase

90% of the cycle, cell performs normal functions, double everything, and grows in size, chromosome duplication ; G1=growth, S=sister chromosomes form, G2=cell organelles duplicate

Mitotic (M) phase

Part of the cell cycle were the cell is actually dividing; includes Mitosis and Cytokinesis= two genetically identical daughter cells

Mitosis

The nucleus and its contents, most importantly the duplicated chromosomes, divide and are events distributed, forming to daughter nuclei

Cytokinesis

The cytoplasm is divided into two

4 STAGES OF MITOSIS

1. Prophase: Nuclear membrane gone

2. Metaphase: Chromosomes line up in the middle

3. Anaphase: Chromosome go apart (yay! :))

4. Telophase: Pinching and growing apart of soon to be 2 cells

Cleavage furrow

An indentation at the equator of a cell during telophase (pinching)

Cell Plate

disk containing cell wall material that develops in plant cells during cytokinesis, eventually dividing the cell into two daughter cells

Cell Control System

Consists of specialized proteins, which send "stop" and "go-ahead" signals at certain points during the cell cycle

Cancer

Disease of the cell cycle, cells do not respond normally to the cell cycle control system, a malignant tumor

Tumors

Abnormally growing masses of body cells

Benign Tumor

Tumors that have not spread into surrounding tissue

Malignant Tumor

Tumors that have spread to other parts of the body and interrupt body functions

Metastasis

Spread of cancer cells beyond their original site of orgin

Radiation Therapy

damages DNA and disrupts cell division

Chemotherapy

Use of drugs to disrupt cell division

Meiosis

Sexual reproduction, fertilization and produces offspring that contain a unique combo. of genes from their parents

Somatic Cell

A typical human body cell that has 46 chromosomes

Karyotype

An image that reveals an orderly arrangement of chromosomes

Homologous Chromosomes

Matching pairs of chromosomes that can possess different versions of the same genes.

Sex Chromosomes

Determine a persons sex, Father Chromosomes determine the sex

Males=XY

Female=XX

autosomes

The remaining chromosomes found in both male and females (everything but XX, XY)

Diploid Organisms

Body cells contain two sets of chromosomes/ pairs of homologous chromosomes

Haploid Organisms

A cell with a single chromosome set, has only one member of each pair of homologous chromosomes

Fertilization

A haploid sperm fuses with a haploid egg

Zygote

A fertilized egg

How Meiosis Halves chromosome number

LOOK AT PIC

Process of Meiosis

LOOK AT PIC

Comparing Mitosis and Meiosis

LOOK AT PICK

Independent Assortment of Chromosomes

Every chromosome pair orients independently of all others at metaphase I. We can't predict which chromosomes (genes) organisms will end up with

Random Fertilization

Human eggs are fertilized randomly, 70 trillion different possible chromosome combination (wooooowwww)

Crossing over

The exchange of corresponding segments between non sister chromatids of homologous chromosomes which occurs during prophase I of meiosis; creates more variations

Genetic recombinations

The production of gene combinations different from those carried by the chromosomes; combine genetic information from different parents because of crossover

Nondisjunction

The members of a chromosome pair fail to separate at anaphase, producing gametes with a incorrect number of chromosomes

Trisomy 21/ Down Syndrome

Individual has an extra chromosome 21, 1 out of every 700 children

Heredity

the transmission of traits from one generation to the next

The science of genetics has ancient roots dating back to the Greek physician

Hippocrates

genetics

the scientific study of heredity

character

a heritable feature that varies among individuals

(ex. flower color)

trait

a variant of a character (ex. purple, white flowers)

heritable factors

today we call genes

self-fertilize

the eggs of one plant are fertilized by the sperm of the same plant (e.g., pea plants)

cross-fertilization

process by which sperm from one flower's pollen fertilizes the eggs in a flower of a different plant

true-breeding

organisms that produce offspring identical to themselves if allowed to self-pollinate

hybrids

the offspring of two different purebred varieties

genetic cross

the cross fertilization of two different purebred varieties (also called hybridization)

P generation

the true-bred parent generation

F1 generation

the hybrid offspring of two different P generations

F2 generation

the offspring of two F1 generations

Monohybrid Cross

a cross where the parent plants differ in only ONE character (like the color of the flower)

Mendelian Principles

1. There are alternative versions of genes that account for variations in inherited characteristics

2. For each inherited character, an organism inherits two alleles, one from each parent.

3. If two alleles of an inherited pair differ, then one determines the organism's appearance (Dominant) and one has no noticeable effect (recessive)

4. Law of segregation: A sperm or egg carries only one allele for each inherited character because the two alleys for a character separate from each other during the production of gametes

alleles

the alternative versions of a gene; an organism inherits two alleles, one from each parent

homozygous

organism that has two identical alleles for a gene

heterozygous

when there are two different alleles for a gene

dominant allele

the allele that determines the phenotype and organism's appearance; written in uppercase

recessive allele

the allele that has no noticeable affect on phenotype or organism's appearance; written in lowercase

Mendel's law of segregation

A sperm or egg carries only one allele for each inherited character because the two alleles for a character separate from each other during the production of gametes

Punnett Square

a diagram used to determine the possible offspring from a cross

phenotype

an organism's physical appearance

genotype

an organism's genetic makeup

dihybrid cross

mating between parental organisms with two differing traits

locus (loci)

a specific location of a gene along the chromosome

Mendel's law of independent assortment

states that the inheritance of one character has no effect on the inheritance of another

testcross

a mating between an individual of dominant phenotype but unknown genotype with a homozygous recessive individual to determine the unknown genotype

rule of multiplication

A statistical rule stating that the probability of two independent events occuring together is the product of their individual probabilities. (e.g., 1/2 * 1/2 = 1/4)

rule of addition

A rule stating that the probability that an event can occur in two or more alternative ways is the sum of the separate probabilities of the different ways. (e.g., 1/4 + 1/4 = 1/2)

wild-type traits

traits that are not necessarily specified by dominant alleles but are seen more often in nature

pedigree

A chart or "family tree" that tracks which members of a family have a particular trait

carriers

parents; people who carry a trait, esp a disorder

cystic fibrosis (CF)

A hereditary disorder characterized by excess mucus production in the respiratory tract; most common life-threatening genetic disease in the US

inbreeding

a mating between close blood relatives

Huntington's disease

rare disease, affects motor and memory, is inherited disease that does not manifest until midlife.

amniocentesis

(pregnancy) extraction by centesis of amniotic fluid from a pregnant woman (after the 15th week of pregnancy) to aid in the diagnosis of fetal abnormalities

chorionic villus sampling

sampling of placental tissues for prenatal diagnosis of potential genetic defects

ultrasound imaging

A technique for examining a fetus in the uterus. High-frequency sound waves echoing off the fetus are used to produce an image of the fetus.

achondroplasia

a form a dwarfism where the head and torso develop normally, but the arms and legs are short

complete dominance

the dominant allele has the same phenotypic effect whether present in one or two copies

incomplete dominance

F1 generation hybrids fall between the phenotypes of the two parents ( white chicken + black chicken = all gray chicks)

ABO blood groups

Involve 3 allele of a single gene, produce 4 phenotypes

codominant

both alleles are expressed in heterozygous inviduals (like AB blood versus just A or just B)

pleiotropy

when one gene influences several characters

sickle-cell disease

disease that makes red blood cells produce abnormal hemoglobin proteins

polygenic inheritance

the additive effects of two or more genes on a single phenotypic character (opposite of pleiotropy)

chromosome theory of inheritance

states that genes are located at specific positions on chromosomes and that the behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns

linked genes

Genes located on the same chromosome that tend to be inherited together in genetic crosses.

sex-linked gene

a gene located on a sex chromosome

linkage map

genetic map that shows the location of genes on a chromosome

sex chromosomes

X and Y chromosomes = determine sex of an individual

red-green colorblindness

a common sex-linked disorder that is caused by a mafunction of light-sensitive cells in the eyes

hemophilia

a sex-linked recessive trait that causes those affected to bleed excessively when injured

Duchenne muscular dystrophy

A human genetic disease caused by a sex-linked recessive allele; characterized by progressive weakening and a loss of muscle tissue.

Nucleotide

The sub-unit of nucleic acids (DNA, RNA) consisting of a sugar, phosphate and a nitrogenous base.

Sugar-phosphate Backbone

A repeating pattern of sugar-phosphate-sugar-phosphate that make up the sides of the DNA ladder.