C8: Cell Division

Anaphase

sister chromosomes are separated into two distinct chromosomes and move towards opposite ends of the cell.

Anti-parallel

refers to the opposite orientations of the 2 strands of DNA, where one is 5' to 3' and the other is 3' to 5'

Aster

radial microtubules that come from the centrioles

Binary fission

Asexual reproduction by division of one cell or body into two nearly equal parts; occurs in prokaryotic cells.

Cancer

uncontrolled growth of cells

Cell cycle

repeating sequence of growth and division through which cells pass each generation

Cell division

part of the cell cycle comprised of mitosis and cytokinesis

Cell plate

the structure that forms at the equator of the spindle during early telophase in plant cells (and some algae)

Centrioles

organelle in animal cells that organizes spindle fibers during mitosis and meiosis

Centromere

point of constriction on a chromosome that contains repeated DNA sequences that bind specific proteins that make up the kinetochore (where microtubules attach during cell division)
Chromatids -One of the two daughter strands of a duplicated chromosome that is joined by a single centromere.

Chromatin

complex of DNA and proteins of which eukaryotic chromosomes are composed

Cleavage furrow

a pinching in of an animal cell's circumference when cytokinesis is dividing the cell into two distinct cells.

Cytokinesis (C)

the cell is split into two new daughter cells

Deletion

a point mutation in which a base of the DNA sequence is lost. This changes the reading frame.

Diploid (2n)

having 2 sets of chromosomes; occurs in body cells

DNA polymerase

enzymes that synthesize DNA from a preexisting template in the 5' to 3' direction and require a primer to extend.

Euchromatin

part of chromosome that is transcribed into mRNA; contains active genes that are not tightly condensed during inter phase.

Eukaryotes

type of cells that have a nucleus

5' end

the end of a DNA nucleotide that had a phosphate attached.

G0

a resting stage. Cell carries out its normal function

G1

cell growth phase where general transcription, translation, and other cell activities take place

G2

cell prepares to separate newly formed DNA and undergo cell division

Haploid (n)

having only one set of chromosomes; occurs in gametes or sex cells

Heterochromatin

Portion of chromosome that isn't transcribed into RNA; remains condensed in interphase and stains intensely

Histones

protein units that make up nucleosomes.

Homologous

refers to a pair of the same kind of chromosome in a diploid cell

Insertion

the DNA has an extra base added into coding sequence which changes the reading frame

Interphase

the period between two mitotic or meiotic divisions in which a cell grows and its DNA replicated (G1, S, G2)

Kinetochore

- disk-shaped protein structure within the centromere to which the spindle fibers attach during cell division. Part of the centromere.

Metaphase

the chromosomes line up in the middle of the cell

Middle lamella

the layer of intercellular material, rich in pectic compounds, that cements together the primary walls of adjacent plant cells.

Mitosis (M)

The nucleus divides

Mutation

a change in DNA

Nucleosome

A complex of a DNA duplex wound around a core of eight histone proteins.

Oncogenes

A mutant form of a growth-regulating gene that is inappropriately "on," causing unrestrained cell growth and division

Plasmid

In prokaryotes, a small fragment of circular DNA that replicates independently of the main chromosome

Primer

a strand of nucleic acid that serves as a starting point for DNA synthesis. It is required for DNA polymerase to bind and begin the process.

Prokaryote

cells without a nucleus; bacteria

Prometaphase

the transitional phase between prophase and metaphase during which the spindle attaches to the kinetochores of sister chromatids.

Prophase

the DNA becomes distinct in chromosome form, nuclear envelope breaks down, spindle fibers form

Semi-conservative replication

refers to DNA replication where each strand of the original duplex serves as the template for construction of a totally new complementary strand, so the original duplex is partially conserved in each of the two new DNA molecules.

Spindles

the structure composed of microtubules radiating from the poles of the dividing cell that will ultimately guide the sister chromatids to the two poles.

Sister chromatids

two newly synthesized copies that originate from the original DNA chromosome; they are identical

Substitution

incorrectly replaced base may change the coding sequence to a different amino acid.

Supercoiling

the winding of double-stranded DNA molecules; results in a condensed version of the chromosome.

S Phase

the DNA (genome) of the organism is replicated; carried out by DNA polymerase

3' end

the end of DNA where DNA replication begins

Telomeres

end parts of chromosomes; Specialized non-transcribed structure that caps each end of a chromosome. They keep chromosomes protected and prevent them from fusing into rings or binding with other DNA. Each time a cell divides, they get a little shorter.

Telophase

the DNA arrives at the poles, the nuclear membrane forms around each set of chromosomes, and the DNA unpackages itself

Template

DNA strand that is used in transcription (RNA synthesis)

Transcription

The enzyme-catalyzed assembly of an RNA molecule complementary to a strand of DNA

Translation

The assembly of a protein on the ribosomes, using mRNA to specify the order of amino acids.

Meiosis

Cell division that reduces the number of chromosomes in daughter cells from the diploid number to the haploid number; produces sex cells

Chromosome

The vehicle by which hereditary information is physically transmitted from one generation to the next; in prokaryotes, it is a single circle of DNA while in eukaryotes, they consist of a single linear DNA molecule and associated proteins

Nonsense Mutation

A base substitution in which a codon is changed into a stop codon. The protein is truncated because of premature termination.

Missense Mutation

A base substitution mutation that results in the alteration of a single amino acid

Silent mutation

the change of one base (2nd or 3rd) does not result in a different amino acid because there are multiple codons that code for the same amino acid. This is referred to the degenerate nature of the genetic code.

Frameshift Mutation

A mutation in which a base is added or deleted from the DNA sequence. These changes alter the reading frame downstream of the mutation.

Point Mutation

a mutation that alters a single base. Deletions, insertions, and substitutions are all types of point mutations.