Mitosis, Meiosis, & Cell Cycle Flashcards
Cell Cycle
Definition:
The series of events that take place in a cell leading to its division and duplication that produces two daughter cells.
Example:
The cell cycle creates new cells.
Checkpoints
Definition:
Insures that the cell is functioning properly.
Example:
Checkpoints prevent cells that are not functioning properly to continue.
Cancer
Definition:
The uncontrolled growth of abnormal cells in the body.
Example:
Cancer is a very deadly disease.
Tumor
Definition:
An abnormal growth of body tissue.
Example:
Once a tumor is big enough, it can start to show.
Mitosis
Definition:
A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus.
Example:
Mitosis is part of the cell cycle.
Identical
Definition:
Being exactly alike.
Example:
Identical daughter cells are produced at the end of mitosis.
Asexual
Definition:
Not involving the fusion of gametes.
Example:
Most cells reproduce asexually.
DNA
Definition:
A molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses.
Example:
All living organisms need DNA.
Chromatin
Definition:
The material of which the chromosomes of organisms other than bacteria are composed.
Example:
Chromatin consists of protein, RNA, and DNA.
Chromosome
Definition:
A threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
Example:
Every human has 46 chromosomes.
Gene
Definition:
A unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.
Example:
Genes are what causes us to look like our parents.
Centromere
Definition:
The point on a chromosome by which it is attached to a spindle fiber during cell division.
Example:
Centromeres are in the middle of a chromosome.
Kinetochore
Defininition:
The point inside a centromere by which a cell is attached to a spindle fiber during cell division.
Example:
Kinetochores are inside centromeres.
Sister Chromatid
Definition:
Pieces of identical DNA that are crucial in the process of cell replication and division.
Example:
Sister chromatids are joined by centromeres.
Parent Cell
Definition:
A cell that divides to produce two or more daughter cells.
Example:
At the beginning of mitosis, there is one parent cell.
Daughter Cells
Definition:
Either of the two cells formed when a cell undergoes cell division by mitosis.
Example:
Each daughter cell is genetically identical to the parent cell.
Interphase
Definition:
The stage in the development of a cell following mitosis or meriosis, during which the nucleus is not dividing.
Example:
Interphase is also considered to be the ‘living’ phase of the cell.
G1 Phase
Definition:
The first growth period of the cell cycle, during interphase, in which the cell grows and cytoplasmic organelles are replicated.
Example:
G1 phase is particularly important in the cell cycle because it determines whether a cell commit to division or to leaving the cell cycle.
G0 Phase
Definition:
A period in the cell cycle in which cells exist in a guiescent state.
Example:
Heart muscle cells and neurons will never enter the G1 Phase, but other G0 cells may.
S Phase
Definition:
The period of the cell cycle prior to mitosis, during which the chromosomes are replicated.
Example:
It is likely that during sleep, most cells go through the S Phase.
G2 Phase
Definition:
A period of rapid cell growth and protein synthesis during which the cell readies itself for mitosis.
Example:
G2 phase ends with the onset of prophase, the first phase of mitosis.
Somatic Cells
Definition:
One of the cells that take part in the formation of the body, becoming differentiated into the various tissues.
Example:
Normally mutations that occur in somatic cells affect only that cell and its descendants which are ultimately dispensable.
Centriole
Definition:
Either of a pair of cylinder-shaped bodies found in the centrosome of most eukaryotic organisms other than plants.
Example:
During cell division, the centrioles move apart to help form the spindle, which then distributes the chomosomes in the dividing cell.
Centrosome
Definition:
A specialized region of the cytoplasm that is located next to the nucleus of a cell and contains the centioles.
Example:
The centrosome is copied only once per cell cycle so that each daughter cell inherits one centrosome, containing two structures called centrioles.
Spindle Fiber
Definition:
One of a network of achromatic filaments that extend inward from the poles of a dividing cell, forming a spindle-shaped figure.
Example:
The spindle apparatus is composed of hundreds of proteins.
Microtubules
Definition:
Any of the tube-shaped protein structures that help eukaryotic cells maintain their hape and assist in forming the cell spindle during cell division.
Example:
Microtubules are very important in a number of cellular processes. They are involved in maintaining the structure of the cell.
Aster
Definition:
A star-shaped structure formed during division of the nucleus of an animal cell.
Example:
Aster is formed around each chromosome during mitosis.
Nuclear Membrane
Definition:
The double membrane surrounding the nucleus within a cell.
Example:
The nuclear membrane has many small holes called nuclear pores that allow material to move in and out of the nucleus.
Prophase, Metaphase, Anaphase, Telophase
Definition:
The four stages of mitosis.
Example:
PMAT is a very important part of the cell cycle.
Prophase
Definition:
The first stage in the process of mitosis.
Example:
In prophase and the later stages of mitosis until separation of the individual chromatids during anaphase, each chromosome consists of two chromatids.
Metaphase
Definition:
The second stage of cell division, between prophase and anaphase, during which the chromosomes become attached to the spindle fibers.
Example:
During Metaphase, the spindle fibers are fully developed.
Anaphase
Definition:
The stage of cell division in which the chromosomes move away from one another to opposite poles of the spindle.
Example:
During Anaphase, the chromosomes are split apart.
Telophase
Definition:
The final phase of cell division in which the chromosomes move to opposite ends of the cell and two nuclei are formed.
Example:
Telophase occurs before Cytokinesis.
Cytokinesis
Definition:
The cytoplasmic division of a cell at the end of mitosis or meiosis, the result being two daughter cells.
Example:
Cytokinesis for plant and animal cells are different.
Cell Plate
Definition:
A plate that develops at the midpoint between the two groups of chromosomes in a dividing cell that is involved in forming the wall between the two new daughter cells.
Example:
The Cell Plate is formed during the stage of cytokinesis for plant cells.
Invagination
Definition:
The morphogenetic processes by which an embryo takes form.
Example:
Invagination is the initial step of gastrulation.
Cleavage Furrow
Definition:
The indentation of the cell’s surface during cytokinesis.
Example:
Plant and animal cells form a Cleavage Furrow differently.
Meiosis
Definition:
A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell.
Example:
Meiosis produces gametes.
Variation
Definition:
Any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences or by the effect of environmental factors.
Example:
Many organisms have variation.
Sexual
Definition:
An organism that reproduces sexually.
Example:
Dogs reproduce sexually, therefore making them sexual.
Homologous Pair
Definition:
Two similar chromosomes in a diploid cell.
Example:
Homologous Pairs pair up during meiosis.
Meiosis 1
Definition:
The first cell division in Meiosis.
Example:
Meiosis 1 generates genetic diversity.
Prophase 1
Definition:
The stage where pairs of homologous chromosomes intertwine and chromosomes swap genetic information.
Example:
The process called crossing over occurs in this stage.
Tetrad
Definition:
A four-part structure that consists of two homologous chromosomes, each composed of two sister chromatids.
Example:
Tetrads form during prophase in meiosis.
Crossing Over
Definition:
Exchange of genetic material between homologous chromosomes.
Example:
Crossing Over occurs during prophase 1 of meiosis.
Synapse
Definition:
A junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.
Example:
Information from one neuron flows to another neuron across a synapse.
Chiasma
Definition:
A point at which paired chromosomes remain in contact during the first metaphase of meiosis, and at which crossing over and exchange of genetic material occur between the strands.
Example:
The chiasma holds the chromosomes together.
Metaphase 1
Definition:
The stage of meiosis where the pairs of chromosomes become arranged on the metaphase plate and are attached to the spindles.
Example:
Metaphase 1 occurs after Prophase 1.
Anaphase 1
Definition:
The stage of meiosis where two chromosomes of each tetrad separate and start moving toward opposite poles of the cell.
Example:
Anaphase 1 contributes to genetic variation.
Telophase 1
Definition:
The stage of meiosis where the chromosomes reach the opposite ends of the cell and the cell pinches in and the membrane begins dividing at the cleavage furrow in a process called cytokinesis.
Example:
At the end of Telophase 1, two haploid cells are formed.
Meiosis 2
Definition:
The second part of the meiotic process, which results in four haploid cells.
Example:
Meiosis 2 occurs in the two cells that were formed during Meiosis 1.
Prophase 2
Definition:
The stage of meiosis where spindle fibers form and begin to move the chromosomes toward the midline of the dividing cell.
Example:
Prophase 2 is the first stage of Meiosis 2.
Metaphase 2
Definition:
The stage of meiosis 2 where chromosomes move to the midline of the dividing cell with each chromatid facing opposite poles of the dividing cell.
Example:
The chromosomes line up differently in Metphase 2 compared to Metaphase 1.
Anaphase 2
Definition:
The stage of Meiosis 2 where the chromatids separate and move towards the opposite poles of the cell.
Example:
The chromatids seperate differently during Anaphase 2 compared to Anaphase 1.
Telophase 2
Definition:
The stage of Meiosis 2 where a nuclear membrane forms around the chromosomes in each of the four new cells.
Example:
During Telophase 2, cytokinesis then occurs resulting in four new cells that contain half of the original cell’s number of chromosomes.
Gametes
Definition:
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.
Example:
Gametes are produced through meiosis.
Nondisjunction 1
Definition:
When at least one pair of homologous chromosomes do not separate.
Example:
The end result of Nondisjunction 1 is two cells that have an extra copy of one chromosome and two cells that are missing that chromosome.
Nondisjunction 2
Definition:
When at least one pair of sister chromatids does not separate during Meiosis 2.
Example:
If Nondisjunction 2 occurs, two cells could have the normal haploid number of chromosomes while one cell will have an extra chromosome and one will be missing a chromosome.
Down Syndrome
Definition:
A condition that occurs when an individual has a full or partial extra copy of chromosome 21.
Example:
Down syndrome the most common genetic condition.
Trisomy 21
Definition:
When each cell in the body has three copies of chromosome 21 instead of the usual two copies.
Example:
Trisomy 21 is not inherited, it is a random event that occurs during cell division.
Haploid
Definition:
Having a single set of unpaired chromosomes.
Example:
A haploid cell has only one set of chromosomes.
Diploid
Definition:
Containing two complete sets of chromosomes.
Example:
Diploid cells contain chromosomes from each parent.
Autosomes
Definition:
Any chromosome that is not a sex-determining chromosome.
Example:
Most chromosomes are Autosomes.
Sex Chromosomes
Definition:
A chromosome involved with determining the sex of an organism.
Example:
If the Sex Chromosomes are XY, then the offspring will be a male. If the Sex Chromosomes are XX, then the offspring will be a female.
