Bio

nucleotides

The small units, or monomers, that make up DNA

double helix

Shape of DNA

Base pair rules for DNA

A-T (adenine-thymine); G-C (guanine-cytosine)

Rosalind Franklin

Woman who generated x-ray images of DNA, she povided Watson and Crick with key data about DNA

Watson and Crick

Developed the double helix model of DNA.

Maurice Wilkins

Used X-ray crystallography to study the molecular structure of DNA. Worked with Franklin (did not collaborate well) to create a picture of the DNA molecule which allowed Watson and Crick to deduce the double helix structure of two strands.

DNA replication

The process in which DNA makes a duplicate copy of itself.

DNA polymerase

a group of enzymes that bond the new nucleotides together

Helicase

An enzyme that untwists the double helix of DNA at the replication forks.

Ligase

An enzyme that connects two fragments of DNA to make a single fragment

Leading strand of DNA

the new complementary DNA strand built continuously along the template strand toward the replication fork in the 5' to 3' direction

Lagging strand of DNA

Strand of DNA built in short segments that are later joined. The lagging strand always moves away from the replication fork and lags behind building of the leading strand. (3-5 direction)

Okazaki fragments

Small fragments of DNA made on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.

Primase

An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template.

cell cycle

the regular pattern of growth, DNA duplication, and cell division that occurs in eukaryotic cells

Gap 1 (G1)

cells grow, carry out normal functions, and replicate their organelles

Synthesis Stage

DNA is replicated

Gap 2 (G2)

Additional growth happens and the cell prepares for mitosis

Mitosis

the division of the cell nucleus and its contents

Cytokinesis

the process that divides the cell cytoplasm

Chromosomes

one long continuous thread of DNA that consist of numerous genes along with regulatory information.

histones

protein molecules around which DNA is tightly coiled in chromatin

Chromatin

long strands of DNA found in the eukaryotic cell nucleus; condense to form chromosomes

Centromere

Area where the chromatids of a chromosome are attached

Chromatid

one half of a duplicated chromosome

telomeres

Repeated DNA sequences at the ends of eukaryotic chromosomes.

prophase

first and longest phase of mitosis, during which the chromosomes become visible and the centrioles separate and take up positions on the opposite sides of the nucleus

metaphase

phase of mitosis in which the chromosomes line up across the center of the cell

anaphase

the third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles

telophase

After the chromosome seperates, the cell seals off, Final Phase of Mitosis.

Cytokenisis (Mitosis)

The cytoplasm divides, in animal cells the cell membrane pinches inward, and in plant cells vesicles from the Golgi apparatus form a cell plate

cancer

A disease in which some body cells grow and divide uncontrollably, damaging the parts of the body around them.

benign

mild, not cancerous

malignant

cancerous

metastasize

the process by which cancer spreads from one place to another

somatic cells

also called body cells, make up most of your body tissues and organs

Gametes

are sex cells - ova, or eggs, in the female, and spermatozoa, or sperm cells, in the male.

homologous chromosomes

Pair of chromosomes that are the same size, same appearance and same genes.

autosomes

chromosomes that contain genes for characteristics not directly related to the sex of an organism

sex chromosomes

Chromosomes that determine the sex of an individual (X and Y chromosomes)

sexual reproduction

involves the fusion of two gametes, resulting in offspring that are a genetic mixture of both parents

Fertilization

the actual fusion of an egg and a sperm cell

Diploid

a cell has two copies of each chromosome: one copy from the mother, and one copy from the father. Represented as 2n.

Haploid

Cell that has only one copy of each chromosome. Represented as n.

Meiosis

a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.

Meiosis I: Prophase I

The nuclear membrane dissolves.

Chromatin tightly coils up.

Homologous chromosomes, each composed of two sister chromatids, come together. Chromatids of homologous chromosomes exchange segments in a process called crossing over.

Meiosis I: Metaphase I

During metaphase I of meiosis, paired homologous chromosomes line up across the center of the cell.

Meiosis I: Anaphase I

Homologous pairs separate and move toward opposite poles of the cell

Meiosis I: Telophase I

Duplicated chromosomes have reached the poles. Usually, cytokinesis occurs along with telophase.

Meiosis II: Prophase II

Chromosomes condense again and become visible. Spindle fibers again form. Nuclear membrane disintegrates again.

Meiosis II: Metaphase II

Duplicated chromosomes align at the cell equator like they are in mitosis.

Meiosis II

the second phase of meiosis consisting of chromatids separating, along with the two diploid cells splitting in two

Meiosis II is similar to mitosis in that

sister chromatids separate during anaphase

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

Klinefelter syndrome

A chromosomal disorder in which males have an extra X chromosome, making them XXY instead of XY.

Monosomy X, called Turner syndrome

In females who have Turner syndrome, one copy of the X chromosome is missing, partially missing or changed.

Trisomy 21 (Down Syndrome)

Genetic disorder resulting from the presence of 3 \#21 chromosomes; characterized by heart and respiratory defects and varying degrees of metal retardation

females have \____ chromosomes

XX

males have \____ chromosomes

XY