Unit III Test Flashcards
When does Meiosis occur? When does Mitosis occur?
Meiosis occurs only with sex cells. Mitosis occurs with every other cell, for growth, repair and replace old cells with new cells.
How many chromosomes are in human body cell?
Humans have 46 total chromosomes arranged in two sets of each.
What is Mitosis?
The distribution of identical genetic material to two daughter cells.
what is a chromosome?
The organized structure of DNA
What is a chromatid?
One of the identical parts of the chromosome after the cell goes through the S-phase (DNA duplication part) of the cell cycle.
Independent Assortment
Meiosis results in a random assortment of genes.
Crossing over
Homologous chromosomes pair up (synapsis). During Prophase I and may exchange portions of chromosomes
What is a zygote?
A diploid cell resulting from the fusion of two haploid gametes, a fertilized ovum.
What an allele?
An allele is an alternative version of gene located on a specific of a specific hormone.
What is a gene?
A gene is a segment of DNA located on a specific site on a specific chromosome that contains information for producing a particular protein (polypeptide)
What is allopatric speciation?
when a population is divided into geographically isolated subpopulations (mountains, rivers, glaciers) or ones that colonize new locations
What is sympatric speciation?
the evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region. For example, Finches
What is disruptive selection?
This occurs when conditions favor individuals at both extremes a phenotypic range over individuals with intermediate phenotypes.
What is stabilizing selection?
Acts against both extreme phenotypes and intermediate favors variants. This mode of selection reduces variation and tends to maintain the status quo for a particular phenotypic character.
What is a genome?
It is one whole set of all the genes plus all of the DNA the genes.
What is polyploidy?
It is an accidents during cell division. It is also an heritable condition of possessing more than two complete sets of chromosomes.
What is speciation?
It is the process of becoming a separate species, over time. (evolution)
Diploid= (2n)
a cell that contains two sets of homologous chromosomes.
Haploid= (n)
A cell that contains a single set of genes (sex cells, bacteria,)
What is a gamete?
It is sex cells (egg, sperm)
What is chromatin?
it is unraveled DNA
What is cytokinesis
the cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells.
What is genetic drift?
is the chance/luck of survival that is not determined by fitness, phenotype, behaviors, etc. Ex: natural disasters occurring in the wrong at the wrong time.
What is sexual selection?
A process in which individuals with certain inherited characteristics are likely than other individuals of the same sex to obtain mates.
What is convergent evolution?
convergent evolution is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.
Interphase (meiosis)
DNA unravels and is copied
Prophase (meiosis)
DNA rewinds and forms back into chromosomes
Metaphase (meiosis)
Chromosomes line up in the middle and spindle fibers attach to the centromere of the chromosome
Anaphase (meiosis)
Copied chromosomes begin to pull apart from each other
Telephase (meiosis)
Two newly formed cells begin splitting
Cytokenisis
When the cell completely split apart
What is directional selection
One extreme phenotype is more fit than all the other phenotypes.
What is The Hardy-Weinberg equilibrium?
The Hardy-Weinberg equilibrium is a principle stating that the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors.
What is a prezygotic barrier?
A reproductive barrier that impedes mating between species or hinders fertilization if interspecific mating is attempted.
What is a postzygotic barrier?
a reproductive barrier that prevents hybrid zygotes produced by two different species from developing into viable, fertile adults.
