Bio #3

Telophase

- the cell elongation that started in anaphase continues -Daughter nuclei appear at the poles of the cells as nuclear envelopes form around the chromosomes. -In terms of chromosomes and spindle structure, telophase is roughly the reverse of prophase. -the mitotic spindle disappears -chromatin fibers uncoil -Mitosis the equal division of one nucleus into two genetically identical daughter nuclei, is finished.

Mitosis

-Only eukaryotic cells undergo mitosis - Mitosis is used to produce daughter cells that are genetically identical to the parent cells. The cell copies - or 'replicates' - its chromosomes, and then splits the copied chromosomes equally to make sure that each daughter cell has a full set.

Cytokinesis 2

-The division of the cytoplasm -In animal cells cleavage furrow forms and the cell pinches into two.

What are codons used for?

. The genetic instructions for the amino acid sequence of a polypeptide chain are written in DNA and RNA as a series of three-base words called codons. b. Three-base codons in the DNA are transcribed into complementary three-base codons in the RNA, and then the RNA codons are translated into amino acids that form a polypeptide.

Gene

A gene is a locus (or region) of DNA that encodes a functional RNA or protein product, and is the molecular unit of heredity

What is the result of translation?

A new protein

Sister chromatids

A sister chromatid refers to either of the two identical copies (chromatids) formed by the replication of a single chromosome, with both copies joined together by a common centromere

Nondisjunction

An accident of meiosis or mitosis in which a pair of homologous chromosomes or a pair of sister chromatids fail to separate at anaphase.

Anaphase

Anaphase begins when the two centromeres of each chromosome come apart, separating the sister chromatids. Motor proteins of the kinetochores powered by ATP "walk" The poles are moved farther apart at the termination of anaphase, the two ends of the cell have equal collections of chromosomes.

Mutation

Any change in the nucleotide sequence of a cells DNA is called a mutation.

Metaphase

At Metaphase, the mitotic spindle is fully formed, with its poles at opposite ends of the cell. The chromosomes convene on the metaphase plate, an imaginary plane equidistant between the two poles of the spindle. For each chromosome, the kinetochores of the two sister chromatids are attached to the microtubules from opposite poles.

At what point does a cell undergoing meiosis become a haploid.

Cells become haploid following telophase 1 of meiosis

Chromatin

Chromatin is a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells.

What is the Flow of Genetic Information?

DNA contains the intstructions for building a protein. DNA transfers the instructions to an RNA molecule in a process called transcription. the NA moves out into the cytoplasm, where its instructions are read and the protein is assembled in a process called translation.

How do the nucleotides for DNA and RNA differ?

DNA is better at forming double stranded molecules; DNA has an H where RNA has an OH (on the sugar)

Cytokinesis

During cytokinesis, which usually begins before mitosis ends, the cytoplasm is divided in two.

Prophase (Meiosis 1)

Early in this phase, homologous chromosomes, composed of two sister chromatids, come together as pairs, a process called synapsis. the new structure consisting of four chromatids aligned gene by gene is called a tetrad. During synapsis, chromatids of homologous chromosomes exchange segments in a process called crossing over. Because the versions of some genes on a chromosome differ from those on its homolog, crossing over rearranges genetic information. As prophase 1 continues chromosomes tightly coil and a spindle forms

Mitosis

In mitosis, the nucleus and its contents- most important, the duplicated chromosomes- divide and are evenly distributed. forming two daughter nuclei

Interphase

Interphase is the period of cell growth when the cell synthesizes new molecules and organelles. At the point shown in the illustration, during late interphase (G2) the cell has doubled much of its original contents and the cytoplasm now contains two centrosomes. Within the nucleus, the chromosomes are duplicated. but they cannot be distinguished individually because they are still in the form of loosely packed chromatin.

Interphase (Meiosis 1)

Like mitosis, meiosis is preceded by an interphase, during which the chromosomes duplicate. at the end of interphase, each chromosome consists of two genetically identical sister chromatids attached together. The cells centrosome has also duplicated by the end of this interphase.

Frameshift Mutations

Mutations involving the insertion or deletion of one or more nucleotides in a gene, called frameshift mutations, often have disastrous effects. Because mRNA is read as a series of nucleotide triplets (codons) during translation, adding or subtracting nucleotides may alter the reading frame of the genetic message.

Homologous chromosomes

One chromosome of each homologous pair comes from the mother (called a maternal chromosome) and one comes from the father (paternal chromsosome). Homologous chromosomes are similiar but not identical. Each carries the same genes in the same order, but the alleles for each trait may not be the same

G2 Phase

Second gap, cell grows more as it completes preparations for cell division.

centromere

The centromere is the part of a chromosome that links sister chromatids.

Cytokinesis & Mitosis

The combination of mitosis and cytokinesis produces two genetically identical daughter cells, each with a single nucleus, surrounding cytoplasm stocked with organelles, and a plasma membrane. Each newly produced daughter cell may then proceed through G1 and repeat the cycle.

Diploid V.S Haploid

The difference between haploid and diploid cells is related to the number of chromosomes that the cell contains. ... Diploid cells contain two complete sets (2n) of chromosomes. Haploid cells have half the number of chromosomes (n) as diploid

Know the base pair combinations for DNA and RNA

The double helix of DNA needs to "unzip" so the complimentary base pairs can connect. Complimentary base pairings means that for each base, there is another base that connects and can ONLY connect with that strand: Adenine with Thymine. (A-T) Cytosine with Guanine. (C-G) Thymine with Adenine. (T-A) Guanine with Cytosine. (G-C)

Codon

The genetic instructions for the amino acid sequence of a polypeptide chain are written in DNA and RNA as a series of nonoverlapping three-base words called _______

Mitotic phase

The interval of the cell cycle when the cell physically divides, accounts for only about 10% of the total time required for the cell cycle. the mitotic phase is divided into two overlapping stages, called mitosis and cytokinesis.

Mitotic spindle

The mitotic spindle is the macromolecular machine that segregates chromosomes to two daughter cells during mitosis. Composed tubulin, motors, and other molecules.

Metaphase 1

The pairs of homologous chromosomes (the bivalents), now as tightly coiled and condensed as they will be in meiosis, become arranged on a plane equidistant from the poles called the metaphase plate. • Spindle fibers from one pole of the cell attach to one chromosome of each pair (seen as sister chromatids), and spindle fibers from the opposite pole attach to the homologous chromosome (again, seen as sister chromatids).

Transcription

The synthesis of RNA under the direction of DNA.

Translation

The synthesis of protein under the direction of RNA.

Silent Mutation

When both code for the same amino acid

Prophase

Within the nucleus, the chromatin fibers become tightly coiled and folded, forming discrete chromosomes that can be seen with the light microscope. The mitotic spindle begins to form as microtubules rapidly grow out from the centrosomes, which begin to move away from each other.

Interphase

___________ is the phase of the cell cycle in which a typical cell spends most of its life. _________ is the 'daily living' or metabolic phase of the cell, in which the cell obtains nutrients and metabolizes them, grows, reads its DNA, and conducts other "normal" cell functions.

Gamete

a mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote.

anticodon

a sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to a complementary codon in messenger RNA.

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. -Genetic variation can occur through crossing over -one round of division

Binary Fission

binary fission, is a form of asexual reproduction and cell division used by all prokaryotes

Missense Mutation

changes one amino acid to another one.

Anchorage dependence

density-dependence, or density-dependent restriction, describes a situation in which population growth is curtailed by crowding, predators and competition. In cell biology, it describes the reduction in cell division.

Density dependent inhibition

density-dependence, or density-dependent restriction, describes a situation in which population growth is curtailed by crowding, predators and competition. In cell biology, it describes the reduction in cell division.

G1 Phase

first gap

locus

in genetics, is the specific location or position of a gene, DNA sequence, on a chromosome.

What are the three components of the nucleotide?

nucleotides = nitrogenous base + pentose + phosphate

Where in the cell does transcription occur?

nucleus

S phase

synthesis of DNA, Chromosomes are duplicated during this phase.

Prometaphase

the nuclear envelope breaks into fragments and disappears. Microtubules emerging from the centrosomes at the poles (ends) of the mitotic spindle extend into the nuclear region, reaching the chromosomes. each sister chromatid has a protein structure called a kinetochore (shown as a black dot) Forces exerted by protein "motors" associated with spindle microtubules move the chromosomes toward the center of the cell.

Anaphase 1

•Anaphase I begins when the two chromosomes of each bivalent (tetrad) separate and start moving toward opposite poles of the cell as a result of the action of the spindle. •Notice that in anaphase I the sister chromatids remain attached at their centromeres and move together toward the poles. A key difference between mitosis and meiosis is that sister chromatids remain joined after metaphase in meiosis I, whereas in mitosis they separate.