Studied by 5 peopleWhat differences found in species' population does natural selection act on?
different phenotypes
What makes these different phenotypes possible within a species population?
genetic variation
Genetic variation is species' populations results in more members of the species being able to do what?
survive a changing environment
How is genetic variation stored in a species' population?
gene pool
The gene pool for all the individuals within a population includes what from all the individuals of that population?
combined alleles
What are the three main sources of genetic variation?
mutations, recombination, hybridization
What do mutations result in a random change in? What can these mutations form?
DNA of a gene; a new allele
During what process do new allele combinations form in offspring through parental alleles changing places?
recombination
In what process of genetic replication does recombination occur most often?
meiosis
What term is given to the crossing of two different species that share common genes?
hybridization
When the value of the distribution of traits is shown on a graph, what term describes the most common traits?
mean
Which type of phenotypes are less common in species' phenotype distribution?
extreme phenotypes
How are extreme phenotypes represented on a graph showing trait distribution?
a drop on each side of the bell-curve
What would result in less common phenotypes being more advantageous to a population?
environmental conditions changing suddenly
What are the three different paths through which natural selection can change the distribution of a trait?
directional, stabilizing, disruptive
What becomes more common in directional selection?
extreme phenotypes
Which kind of phenotype becomes more common in the species' population during stabilizing selection?
intermediate
What happens to the most common traits in a species' population during disruptive selection?
dramatically decline over time
Gene flow occurs when individuals of the same species do what?
move between populations
What increases as a result of gene flow?
genetic variation
What effect does genetic drift have on the genotypes of a species' population?
loss of genetic diversity
What are two main processes of genetic drift?
bottleneck, founder
Both sexes of a species benefit from their offspring being able to do what?
survive
What does a female ensure for her offspring by choosing the best mate possible?
best genetics possible
What are the two types of sexual selection?
intersexual, intrasexual
Males of a species convince females that they possess what two qualities during intersexual selection?
healthy and good genetic quality
Gene
specific region of DNA that codes for a particular protein
Allele
any of the alternative forms of a gene that occurs at a specific place on a chromosome
Genome
all of the organisms genetic material
Genotype
collection of all of an organism's genetic information that codes for traits
Phenotype
collection of all of an organism's physical characteristics
Dominant
allele that is expressed when two different alleles are present in an organism's genotype
Recessive
allele that is not expressed unless two copies are present in an organism's genotype
Testcross
cross between an organism with an unknown genotype and an organism with a recessive phenotype
Crossing over
exchange of genetic material between homologous chromosomes during prophase I of meiosis
What term is given to the specific location of genes on a chromosome?
locus
What are alternative forms of a gene called?
allele
How many alleles do cells have for each gene?
2
Which type of allele is expressed when 2 different alleles or 2 dominant alleles are present on a chromosome?
dominant
Which type of allele is expressed when 2 copies of a recessive allele are present on a chromosome?
recessive
What is commonly done by scientists while studying genetics?
focusing on a single trait
Besides genotype, what also interacts with genes and affects their expression?
phenotype
What was the profession of R.C, Punnett?
poultry geneticist
What type of system did Punnett develop for predicting all possible genotypes resulting from a genetic cross?
punnett square
By counting the number of squares in a genetic combination, what can be figured concerning genotypes?
ratio
What process restores the diploid number in offspring?
fertilization
List the three types of monohybrid crosses?
homoXhomo; heterXheter; heterXhomo
What type of phenotype must an organism have in order for a testcross to be necessary?
recessive
What was the phenotypic ration that Gregor Mendel consistently obtained in the second generation of breeding?
9:3:3:1
What name is given to Medndel's second law of genetics?
law of independent assortment
According to the law of independent assortment, how do allele pairs separate during meiosis?
independently
Which type of outcomes are predicted through the use of the mathematics called probability?
heredity patterns
What is a major advantage of sexual reproduction that is produced within a species?
genetic variation
In the formation of gametes, how many different possible human chromosome combinations are there?
8 million
What are mixed during the joining of gametes during fertilization?
alleles
How many possible genetic combinations are there i the joining of two human gametes?
70 trillion
What is ensured for organisms through sexual reproduction? What does this result in for the organism?
unique combination; unique phenotypes
What is another term for the process of ensuring genetic diversity called crossing over?
recombination
When does crossing over occur?
prophase I of meiosis I
What affects the likelihood of weather genes are separated when crossing over happens?
the farther apart the genes are
Which kind of genes tend to be inherited together?
closely located
What have scientists been able to build for many species by exploring relationships between many genes?
genetic map
Probability
likelihood that a particular event will happen
Somatic Cells
cell that makes up all of the body tissues and organs, except gametes
Gamete
sex cell; an egg or a sperm cell
Autosome
chromosome that contains genes for characteristics not directly related to the sex of the organism
Sex Chromosome
chromosome that directly controls the development of sexual characteristics
Fertilization
fusion of an egg and sperm cell
Meiosis
form of nuclear division that divides a diploid cell into haploid cells; important in forming gametes for sexual reproduction
Gametogenesis
process by which gametes are produced through the combination of meiosis and other maturational changes
Trait
characteristic that is inherited
Genetics
study of the heredity patterns and variation of organisms
Cross
mating of two organisms
What are the two major groups of cells that make up organisms?
somatic and germ clls
For each somatic cell, what does each species have a characteristic number of?
chromosomes
How many chromosomes do humans have?
46
How many pairs of chromosomes do humans have?
23
Which type of cells make up most of an organism's body tissues and organs?
somatic cells
Which two types of gametes make up the germ cells of an organism?
egg and sperm
What two characteristics do homologous chromosomes have in common?
length & general apperance
What letters are given to the 23rd sex chromosome in the human genome?
X & Y
Sexual reproduction involves the fusion of what?
gametes(sperm & egg)
Which type of body cells are diploid?
somatic
Which type of body cells are haploid?
gametes
What happens to the nucleus during the process of meiosis?
divides & makes four haploid cells
In meiosis, how many phases are there to each round of cell division?
4
Which type of chromosome are divided in meiosis I?
homologous chromosome
Which type of chromosome are divided in meiosis II?
sister chromatid
What type and number of cells are produced in meiosis I?
two cells with 23 duplicated chromosomes
Is DNA duplicated during meiosis I?
NO
What type of cells are produced at the end of meiosis II?
4 haploid cells
Differences in the final stages of gametogenesis are based upon what?
gender of the parent
Which type of cell contains the DNA of the male gamete?
sperm cell
Which cell organelle provides sperm cells with the energy needed for the cell's survival and movement?
mitochondria
Which type of cell contains the DNA of the female gamete?
egg cell
For mammals, when does egg formation begin inside the female body?
before birth inside the embryo
What term is given to distinguish characteristics that are inherited?
traits
Who is given credit for establishing the study of genetics as a modern science?
Gregor Mendel
What was Mendel's profession?
austrian monk
What type of plants did Mendel use in his genetic studies?
pea plants
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