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One of the characteristics of living things is their ability to ... ?
Reproduce their kind
Heredity is the transfer of biological information from ... ?
Parent to offspring
Genetics is the branch of biology concerned with the structure, transmission, and ... ?
Expression of hereditary information
Genes are the ... ?
Units of heredity
Chromosomes (colored bodies) are the nuclear packages in which ... ?
Genetic information is stored
Chromosomes are composed of a tangle of darkly staining fibers called ... ?
Chromotin is composed of ... ?
60% protein, 35% DNA, and 5% RNA
THe length of DNA in a single cell nucleus is estimated to be ... ?
About 1 yard
Each chromosome contains .... ?
Thousands of genes
Each gene is a unit of information which determines a specifically hereditary trait and occupies a ... ?
Specific location on a chromosome
Some genes are capable of transmitting their chromosomal ... ?
DNA information to RNA molecules
RNA molecules contain the code sequence of amino acids (the building blocks of proteins) of all proteins produced ... ?
Within the organism
Humans have ... ?
About 75,000 genes
Everyy individual in a given species possesses a specific number of chromosomes. These chromosomes occur in ... ?
Virtually every cell of the body.
Human body cells have 46 chromosomes. For this reason 46 is termed the ... number?
The somatic number is also identified as the ... number?
Diploid number (2n)
The number of chromosomes present in the sex cells gametes) is 23. This is the ... number ?
Haploid number (1n)
The number of chromosomes between animal species varies from 2 to several hundred (The crayfish has 200 chromosomes). Many species other than man ... ?
Also have 46 chromosomes
Once cells reach a certain size, they must stop growing or divide. However, some cells do not normally divide. What are three of these types ?
Nerve cells, cardiac muscle cells, and mature red blood cells (RBCs)
The cell cycle includes all the activities of the cell during which it is ... ?
Actively growing and dividing
The completing of the cell cycle is termed .... ?
The time to duplicate an average cell is ... ?
About 24 hours
The cell cycle is divided into ... ?
In the M (mitosis) phase, active cell division occurs and lasts about .... ?
In the G1 (gap 1) phase, organelles begin to double in number and this phases lasts about... ?
In the S (synthesis) phase, the DNA replicates and this phase lasts about ... ?
In the G2 (gap 2) phase, synthesis of proteins occurs and this phases lasts about ... ?
Mitosis occupies approximately ... ?
5% of the total cell cycle
Cell duplication involves ... ?
2 main processes
Mitosis (greek for threads) is a division of the nucleus that produces an equal sharing of the chromosomes by the ... ?
2 resulting cells
Cytokinesis is the division of the cytoplasm that is ... ?
Coincident with mitosis
The 5 phases of mitosis are ... ?
Interphase, Prophase, Metaphase, Anaphase, and Telophase.
What's the first phase of mitosis?
What's the second phase of mitosis?
What's the thirdphase of mitosis?
What's the fourth phase of mitosis?
What's the five phase of mitosis?
Interphase is the normal working phase of the clel. Structures and substances such as organelles are being .... ?
Synthesized and accumulated
Does any cell division take place during Interphase?
Interphase lasts about 95% of the cell cycle and the chromatin in the nucleus is "unorganized". The individual chromosomes are not .... ?
In prophase, the nuclear membrane and .... disappear?
In Prophase, the chromatin begins to "organize" by coiling and folding and becoming thicker. During this process, the individual ... ?
Chromosomes become visible
During organization in Prophase, the chromosomes, which duplicated during the S-phase of the cell cycle are called .... ?
Prophase: The constructed part of the chromosome that joins the sister chromatids is called ....
Prophase: Each sister chromatid has a long or short arm which extends from the centromere. The short arm is identified by the letter ... and ... ?
"p" and the long arm by "q".
In animal cells, the centrosome, and the two centrioles contained within it, duplicate and migrate to opposite ends (poles). Centrioles are not found in plants, although... ?
The centrosome is.
Prophase: As each pair of centrioles migrate to their respective poles, they pull one set of microtubule ends after them. The other set of ends are connected to the centromere halves...
Termed the kinetochore
Microscopically, the centrioles and their associated microtubules somewhat resemble starbursts and are ... ?
Called asters (stars)
During aster formation the chromosomes begin to organize along the ... ?
Center (equator) of the cell
The appearance of the 2 asters, with their microtubules radiating to the cell's equator, is known as ... ?
The mitotic spindle
Metaphase: The chromosomes line up along the equator of the cell with the centromeres are...
The equators midline
Metaphase: The mitotic spindle is complete. SPindle fibers can be seen to run from the polar centrioles to each ... ?
Centromere on the equator
Metaphase: The chromosomes are very distinct and are ... ?
Used for genetic studied at this stage
Anaphase: Sister chromatids separate at their centromeres. At this point they become ... ?
Anaphase: The separated chromosomes are pulled to opposite poles by their ... ?
Attached spindle fibers
Anaphase: Anaphase ends when all the chromosomes have ... ?
Reached the poles
Telophase: The chromosomes begin to uncoil to form ... ?
Telophase: The spindle ... ?
Telophase: The nucleolus ... ?
Telophase: The cytoplasm divides forming the two daughter cells with the ... ?
Return to interphase
Cytokinesis: Cytokinesis is the division of the cytoplasm in .... ?
The formation of daughter cells
Cytokinesis: It begins during ... ?
Cytokinesis: A cleavage furrow forms--the precursor of the cell membrane. This furrow deepens forming a contractile ring until two new cells develop ... ?
Each with a new complete nucleus
Cytokinesis: In plants, a cell plate forms which is ... ?
Part of the cell wall
Mitosis: Each replicated cell receives exactly the same chromosomes .... ?
As the original cell
Mitosis: The cytoplasmic organelles are evenly distributed during cytokinesis and .... ?
Replicate by themselves
Mitosis is ... , not sexual.
The daughter cells are exact clones ... ?
Of the original cell
The significance of meiosis is to half the number of chromosomes during gamete formation (... ?)
To maker smaller
Involves .... ?. There are 2 parents.
Each parent contributes a specialized sex cell (hamete). The gamete is ... ?
The male gamete is the ... ?
The female gemete is the ... ?
Gemetogenesis is the development of gametes and occurs ... ?
In the gonads
Male gonads are ... ?
Female gonads are ... ?
During fertilization, the sperm and egg fuse to form a zygote (2n). Subsequent divisions ... ?
The net effect of meiosis is to provide the offspring with the ... ?
Genetic background of both parents
The chance of combinations of these haploid gametes can result in zygote configurations (mutations) that are new for the species. The good combinations tend to .... ?
Survive; and the bad do not.
There are two cell divisions, but the chromosomes are only duplicated once. In mitosis there is one cell division with ... ?
One duplication of chromosomes
All the resulting cells are ... ?
In a diploid somatic (body) cell, chromosomes ... ?
Occur as pairs
Each set of chromosomes is a homologous pair and each member is a ... ?
Homologous chromosome or homologue or chromatid.
One member of the homologous pair was inherited from the female parent; the ... ?
Other was inherited from the male parent.
Homologues look alike. THey have the same length, centromere position, and ... ?
A specific location on one homologue contains the same gene that occurs at the same location on its ... ?
First meiotic division: this phase is also called meiosis 1 or .... ?
Prior to meiosis 1, DNA replication occurs forming 2 sister chromatids for ...
During meiosis 1, homologous chromosomes come together and line up on the equator side by side. This is termed .... ?
In synapsis, the two sets (pairs) of homologous chromosomes are ... ?
Described as tetrads or bivalents
Crossing-over .... ?
Occurs at this point
Nonsister chromatid arms cross each other at various points in a .... ?
Seemingly arbitrary fashion
The points where the arms cross are termed chiasmata (singular: chiasma), and serve as junctures where the arm of one chromatid is exchanged for ... ?
That of its sister chromatid.
Because of crossing-over, the genetic instructions from a father and a mother are mixed, and the daughter cells receive .... ?
Chromosomes with recombined genes.
Crossing over increases genetic ... ?
The homologues of each tetrad separate and move to opposite poles. The centromeres remain intact, meaning ...
They do not cleave
Cytokinesis separates the 2 daughter cells ... ?
Which are now haploid
Second meiotic division. This phase is also called ... ?
Meiosis II or equatorial division
No replication of chromosomes .... ?
Occurs at this stage
The centromeres cleave (separate) releasing the 2 sister chromatids, each of which migrates ... ?
To an opposite pole
Cytokinesis separates the 2 sister chromatids which then ... ?
Develop into haploid gametes
Genetic recombination insures that offspring have a different combination of genes than their parents. This occurs as a result of 3 mechanisms. What are they?
1) Crossing-over of nonsister chromatids, 2) Independent assortment of homologous chromosomes, and 3) Fertilization results in combinations of genetically different gametes.
What's the first mechanism?
Crossing-over of nonsister chromatids
What's the second mechanism?
Independent assortment of homologous chromosomes
What's the third mechanism?
Fertilization results in combinations of genetically different gametes
Crossing-over of ... ?
Independent assortment of ... ?
Independent assortment of homologous chromosomes: Independent alignment of tetrads at the equator during meiosis 1 causes the gametes to have ... ?
Different combinations of chromosomes
Comparison of meiosis to mitosis: DNA replication takes place only once during both meiosis and mitosis. However, there are two nuclear divisions during meiosis and ... ?
Only one during mitosis
Comparison of meiosis to mitosis: Four daughter cells (gametes) are produced by meiosis. Mitosis results in ... ?
Two daughter cells
Comparison of meiosis to mitosis: The four gametes formed by meiosis are hapoid. The daughter cells produced by mitosis have the same chromosomal number as ... ?
The parental cell (mother cell)
Comparison of meiosis to mitosis: The four daughter cells from meiosis are not genetically identical to each other or to the mother cell. The daughter cells from mitosis are genetically...
To the mother cell
Meiosis occurs in the gonads during spermatogenesis and ... ?
Oogenesis in humans
Oogenesis occurs in the ... ?
Spermatogenesis occurs in the ... ?
A primary spermatocyte, with 46 chromosomes, divides by meiosis to form two secondary spermatocytes each with ... ?
23 duplicated chromosomes
Secondary spermatocytes divide to produce four spermatids ... ?
Also with 23 daughter chromosomes
Spermatids then differentiate ... ?
Into motile sperm
Meiotic cell division in mals always results in ... ?
Four cells that become sperm
Unlike the four sperm produced from a single primary spermatocyte, only one ovum is generated from each primary oocyte. This conserves cytoplasmic materials to sustain the...
Site within the uterus.
A priamry oocyte, with 46 chromosomes, divides by meiosis to form two cells, each with ... ?
23 duplicated chromosomes
One of the cells, a secondary oocyte, receives ... ?
Most of the cytoplasm
The other cell, a polar body (the first polar body), is ... ?
Discarded and disintegrates
A secondary oocyte begins meiosis II, but then temporarily stops to undergo ovulation, which means ... ?
Release from the ovary
The ovum enters the oviduct (Fallopian tube) where fertilization by a ... ?
Sperm may occur
If a sperm enters the secondary oocyte, the oocyte is activated to continue meiosis II ... ?
Through to completion
Another polar body (the second polar body) is ... ?
Generated and discarded
The result of fertilization is mature diploid cel termed a zygote which becomes the .... ?
First diploid cell of a new individual
Mitosis comes from the Greek word mitos which means ... ?
What process occurs in organisms that reproduce asexually?
What process is absolutely necessary for sexual reproduction to occur?
Eukaryote DNA molecules have large amounts of ______________ dispersed among the DNA molecules.
Each chromosome contains thousands of ... ?
Colored bodies containing genetic information
Concentrated form of a chromatin
Define sister chromatid:
A chromatin is the chromosome in the ... ?
Chromatids that are attached at the Centromere are called what kind of chromatids?
Centromere is the constricted part of the chromatin that joins the sister
Centromere joins duplicated DNA molecules that are called ... ?
Centromere position along the chromosome will not be in the exact location for every chromosome but instead ... ?
Microtubules attach to the kintochore of ... ?
Is a centromere permanent or temporary?
Centromere is the attachment site for ... ?
What makes spindle fibers?
Different organisms have different number of chromosomes. Some organisms have as many as __________________ (for ex. Adder Tongue) chromosomes which indicates that...
All members of the same species will have the same ______________________ of chromosomes
The number of chromosomes remains ? throughout a life cycle
List in proper sequence the stages of Mitosis
Prophase, Metaphase, Anaphase, Telophase (PMAT)
In which stages of mitosis does each chromosome consist of two DNA molecules?
Prophase and Metaphase
Chromatids detach from one another and become visibly separate chromosomes during what state of mitosis?
Anaphase and Telophase
New nuclei are formed during what stage of mitosis?
Are homologous chromosomes paired during mitosis? (yes/no)
Yes and No (wth?)
In .... ? ... chromosomes align at the spindle equator (think stages of mitosis)
In .... ? ... sister chromatids become individual chromosomes (think stages of mitosis)
In .... ? ... centromeres divide (think stages of mitosis)
Prophase (not completely sure about this)
In .... ? ... chromosomes move apart (think stages of mitosis)
In .... ? ... spindle microtubules shorten, pulling chromosomes toward the pole (think stages of mitosis)
Chromosomes are duplicated during ? of the cell’s life cycle
Plants have a rigid cell wall which prevents the plant cell from being pinched in two. Instead vesicles containing remnants of themicrotubular (microtubule) spindle form a disk...
Chromosomes (containing DNA and carrying genes) replicate during _____ of the cell cycle
Chromosomes condense and microtubular spindle develops during this phase of mitosis ... ?
During what stage of mitosis does homologous pairs of chromosomes line up on the equatorial plate? ____
At this stage of mitosis sister chromatids joined at their centromeres are attached to spindle fibers. ________
During this phase of mitosis the centromeres break apart as the separated sister chromatids begin to move to opposite poles. ____ ?
Cytokinesis occurs at the end of ________
New daughter nuclear membranes form during this phase of mitosis. _____
Spindle fibers are about 25nm in diameter and are formed from ______
Physical separation of the cytoplasm occurs during ________
_____ move to opposite poles and form spindle fibers
. Two sister chromatids are joined at the ___________
Chromosome name changes during its life cycle from chromatin to chromatid. What name does it have when it is half of a chromosome in prophase?
Sexual reproduction results in new combinations of genetic _____
If meiosis did NOT occur in sexually reproducing organisms, the chromosome number would ________________ in each generation
Through ________________________, offspring are provided with new gene combinations
Through meiosis, parental DNA is divided and distributed to forming gametes. This results in diploid chromosome number to be reduced to _________________ number
Meiosis allows alternate forms of genes to be _____ This enables offspring to have a new gene combination
Different, or alternative, forms of the same gene are called ______
In meiosis, each gamete receives one member of each pair of homologous chromosomes and ______________ are formed that are haploid
Homologous chromosomes are in pairs, one chromosome from each pair comes from the father and one from the __________
Homologous chromosomes may exchange parts during ____________ of meiosis
Crossing-over (prophase1 )
Crossing over alters the composition of chromosomes and results in new combinations of ___________ that eventually are channeled into the daughter cells
Crossing over is one of the most important events in meiosis because it produces new arrays of ___________ on chromosomes.
If a diploid organism has a genome consisting of 3 chromosomes, it can produce ________ different combinations of maternal and paternal chromosomes (disregarding crossing...
The haploid number for human chromosomes is ____. The diploid number is _____. Altogether there are ______ pairs of chromosomes. Human gametes end up with...
spermatogonium is ... ?
primary spermatocyt ... ?
secondary spermatocyte ... ?
spermatids ... ?
oogonium ... ?
primary oocyte ... ?
secondary oocyt ... ?
ovum ... ?
polar bodies ... ?
Polar bodies do ________________ develop into a gamete
A pine tree is called a sporophyte because it produces spores by (mitosis or meiosis?)