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What is sexual reproduction?
The fusion of a male gamete(sperm) & female gamete(egg) to form a zygote.
What is a gamete?
Single cells, produced by adult organisms, which are specialized for mating; gametes often die if mating is not accomplished.
What are sperm?
What are eggs?
what are zygotes?
Single cells that result from the fusion of gametes. If conditions are favorable, zygotes develop into adults, completeing the reproductive cycle.
What is meiosis?
A nucular division process that reduces the number of chromosomes by one-half. Sexual reproduction cycles of eukaryotes requires meiosis.
Sexual reproduction in eukaryotes is characterized by, what?
Gametes, zygotes, and meiosis.
What are some advantages of sexual reproduction?
- Combines DNA of 2 different organisms, creating new combinations of valuable genetic traits.
- The potenial to colonize new types of environments or adapt to changing conditions.
- It speeds the loss of deleterious genes.
- Allows potentially beneficial genes to escape the influences of inhibitory genes that previously held them in check.
What are some of the advantages of asexual reproduction?
- It requires few resources and less energy than sexual reproduction.
- It does not exspose gametes to the risk of not finding a mate.
- If asexual reproductive structures do not undergo fertilization, they do not die, they develop into new organisms if the environment is stable.
- It requires 1 parent.
- The progney are geneticlly alike, increasing the survival rate in stable environments.
- Is more effective in harsh environments.
Fungai reproduce by small, asexual spores called?
What is phytophthora?
The plant destroyer, it is a microbe which causes diseases in many plants, and reproduces sexually and asexually.
What is sporangia?
Structures that produce and enclose spores.
What are spores?
single-celled reproductive structures that are dispersed from the parent, which can result from both sexual and asexual processess.
what are some examples of plants that reproduce asexually?
- Aspen Tree
What is syngamy?
Is the process by which 2 gametes fuse during sexual mating. Also known as, fertilization.
What is a haploid?
The basic number of chromosomes (1) present in gametes, also known as "N". Some plants N=2, and some can be greater than 500. For humans, N=23
What is a diploid?
- The zygote nuclei contain the total number of all the chromosomes(sets) contibuted by each gamete, the chromosome number(diploid) for the zygote is
- 2N. For humans 2N=46
What are homologous chromosomes?
Members of pairs of chromosomes(one derived from each parent) that are similar in size and gene type. These chromosomes mix together in the process of meiosis, to create a zygote. A human has 23 homologous chromosomes
What are chromatids?
Idenitcal copies of each chromosome that remain attached by a centromere.
What is alternation of generations?
A life cycle in which a haploid (N) gametophyte produces gametes by mitosis that fuse into a diploid (2N) zygote that germinates and grows into a sporophyte. The sporophyte produces spores by meiosis that form new gametophytes.
What are some distinctions of meiosis?
- Meiosis occurs in 2 stages (meiosis 1 & 2).
- It prevents the buildup of chromosomes that would otherwise occur after many generations of sexual reproduction.
- Contributes to genetic variations in populations of organisms by shuffling the chromosomes donated by parents.
- Meiosis provides a oppurtunity for chromosomes to exchange segments, a process known as "crossing over".
What is "crossing over"?
Homologous chromosomes are paired in meiosis 1, they can exchange segments, thereby creating new genetic combinations. This chromosome segment exchange process in known as "crossing over".
What is nondisjunction?
If homologous chromosomes to not seperate at anaphase of meiosis 1, an event known as nondisjunction, abnormal gametes are formed.
What happens in meiosis 1?
It seperates homologous chromosomes, producing 2 haploid cells(N chromosomes, 23 in humans)Also known as reductional division. A regular diploid human cell contains 46 chromatids, it is only considered as being "N", with 23 chromosomes. This is because later, anaphase 1, the sister chromatids will remain together as the spindle fibres pulls the pair toward the pole of the new cell.
What happens in meiosis 2?
An equational division similar to mitosis will occur whereby the sister chromatids are finally split, creating a total of 4 haploids cells (23 chromosomes, N) per daughter cell produced in meiosis 1.
What is mitosis?
A form of nuclear division in which a set of chromosome copies resulting from DNA replication are distributed to progeny cells.
What are the three major types of life cycles?
What happens in the gametic life cycle?
The gametes arise by meiosis, characterizes animals and some algae
What happens in the zygotic life cycle?
Typical of many protists; meiosis occurs during zygote germination.
What happens in the sporic life cycle?
Sexual spores are generated by meiosis, occur in land-adapted plants and some algae, notably giant kelps. Plants and algae with sporic life cycles have 2 alternating multicellular bodies, the sporophyte (which produces sexual spores) and the gametophyte (which produces gametes).
What causes Downs Syndrome?
Nondisjunction, abnormal gametes are formed. In humans, gametes normally have 23 chromosomes. However, nondisjuction can result in gametes having more than 23 chromosomes. If a gamete with (2) 21 chromosomes fuses with a game having normal chromosome number, the child that results will likely suffer from Downs Syndrome or some degree of mental retardation.
Who is Gregor Mendel?
An Austrian monk who experimanted with garden peas, worked out the basic patterns of inheritance of genetic traits in the 1860s.
What is a hybrid palnt?
The result of crossbreeding between 2 varieties, species, or genera.
What is a monohybrid cross?
A cross between 2 varieties that differ in only one trait.
What is segregating?
A term applied to the reapperance of recessive traits in offspring hybrids. The recessive traits reappear because the chromosomes (and their genes) from each parent seperate in meiosis.
What is self-fertilization?
The process the occurs in some plants in which a single flower produces both the male and female gametes that can fuse and produce healthy offspring.
What is cross-fertilization?
In plants, the fusion of gametes derivied from flowers on different varieties.
What is the first filial generation or F1 generation?
The resulting hybird offspring of cross fertilizing 2 different varieties of plant.
The traits expressed in an F1 plant are called, what type of traits?
The traits not expressed in an F1 plant are called, what type of traits?
What is the second filial or F2 plant?
The result when F1 plants self pollenate and the seeds are planted. Gregor Mendel did this to find out what traits would appear in the F2 plant. Some of the F2 individuals produced the recessive trait.
What is the punnett square?
A box diagram developed by British geneticist Reginald Punnett to represent the genetic combinations in a cross between parental varieties.
Explain Mendels first law of heredity?
Also known as the law of segregation. Mendels first law of heredity states that alleles for a gene segregate independently of each other in individuals that pocess both alleles.
What is a testcross?
A cross in which an organism showing the phenotype of the dominant trait is crossed with one showing the recessive trait to determine if the dominant phenotype is homozygous or heterozygous for the domiant trait.
What is an allele?
One of two or more different forms of a gene.
What is the locus?
The site on homologous chromosomes where alleles for a gene are located.
What is homozygous?
An individual that pocesses two copies of the same allele of a gene.
What is heterozygous?
An individual that pocesses two copies of different alleles for a single gene.
What is the phenotype?
The physical characteristic on an organism. In garden peas, for example, purple flower color is a phenotype, but the genotype could be PP or Pp.
What is a genotype?
The genetic makeup of an organism.
Explain incomplete dominance?
A genetic conditon in which neither of the two alleles of a gene is dominant over the other, and the heterozygous individual had a phenotype intermediate between the two homozygous phenotypes.
Polygenes, are what?
Genetic triats that are controlled by several genes, such as height in humans and kernal color in wheat.
As it pretains to genes and chromosomes, what does the term "linked" mean?
Its the genetic condition that arises when 2 or more genes are located close together on the same chromosome. Linked genes tend to be inherited together.
What is genetic combination?
The formation of new combinations of alleles by the exchange of segments between homologous chromosomes.
Explain what a dihybrid cross is?
A cross between individuals or plant varieties that differ in 2 traits.
What is epistasis?
A genetic condition in which two genes combine to produce a trait. A defect in either gene prevents expression of that trait.
What is Mendel's Second Law of Heredity?
Also known as, the Law of Independent Assortment Mendels Second Law that states that genes for different traits located on different non-homologous chromosomes assort independently of each other during meiosis.
What are sex chromosomes?
Designated with X and Y, they are responsible for sex determination.
What are autosomes?
What is hybrid vigor or heterosis?
The phenomenon were hybrids are often larger, more vigorous, and produce larger seed crops than any pure-breeding single variety.
What is GEO?
Geneticlly Engineered Organism
In cell transformation, what methods are available for moving genes to recipient cells?
- Biological organisms, like plasmid and viruses.
- Newer methods like micoinjection, electro and chemical poration, bioballestics.
What are restriction enzymes?
- Enzymes that leave the DNA double helix at specific nucleotude sequences.
- One of 2 tools used for producing recombinant DNA.
What is gene designing?
The transformed plant cell is allowed to divided then treated with hormones to differentiate into a plant.
Where does translation occur?
In the cytoplasm on the rER.
What is genetic engineering?
A set of tools that allows one to alter the genetic makeup of an organism.
What are some of the benefits of geneticlly modified plants?
- Crops grow faster.
- Crops are larger.
- More resistant to pest and disease.
- Reduces pesticides and herbicides.
What is biotechnology?
The genetic manipulation of biological organisms by humans to better suit then for human needs, or industrial applications of biological organisms.
What are the tools for producing recombinant DNA?
- Restriction enzymes.
What is PCR?
Polymearse Chain Reaction, a procedure for amplifying a specific sequence of DNA by subjecting it to numerous cycles of polymerzation followed by seperation of complitmentary strands. 2 DNA primers, one complementary to each end of the selected DNA sequence, are used to amplify the selected sequence.
What are the 3 RNA's used to make protein?
What are the 3 enzymes needed for DNA replication?
What is an example of biotech being used for indenification purposes?
- Paturnity testing.
What are the componets for recombinant DNA?
- A vector (plasmid or virus)
- Gene of interest.
What is backcross breeding?
A new trans-genetic plant is crossed with a high yeilding plant.
DNA is copied in which phase?
What are the major steps in genetic engineering?
- DNA isolation.
- Gene cloning(recombinant DNA technology)
- Cell transformation.
How does one produce recombinant DNA?
- Treat source DNA and plasmid DNA with restriction enzymes.
- Mix together, adding DNA ligase.
- Many recombiant DNA is produced each with a different piece of source DNA.
- Transform bacterial cells.
- Each bacterial cell carries a different recombiant plasmid.
What is central dogma?
When DNA is transcribed to RNA which is translated into protein.
What are some examples of biotech in agriculture?
- Transgenetic animals that provide models for human diseases.
- Producing pharmaceuticals and releasing them in milk.
What is ligase?
- An enzyme used to join fragments of DNA or RNA.
- One of 2 tools needed for producing recombiant DNA.
Where does transcription occur?
In the nucleus.
What is GMO?
Genetically modified organism.
Whats the role of the helicase enzyme in DNA replication?
It unzips the DNA.
What is RFLP analysis and its role?
- Restriction fragment length polymorphism.
- It is used as a probe to indentify specific DNA fragments derived from restriction enzyme digestion.
- Slows variations in sizes of fragments in different individuals.
What is genetic engineering?
Taking genes and segments of DNA from one spices and transferring them to another spices to achieve a desired effect on an organism.
What are examples of biotech in medicine?
- HGH for dwarfism.
- Insulin for diabetes.
- interferon for cancer and MS.
- Gene therpy.
What is recombinant DNA?
A term used to describe the incorporation of foreign DNA into the normal DNA of an organism.
What are some dissadvantages to GM plants?
- Crops become poison to benefical insects.
- pests build up a tolerence to GM crops.
- Plant viruses spread.
How does a cell make protein?
What are transposons?
Plants and other organisms that have pieces of mobile DNA.
What are plasmids?
Small circular pieces of DNA that occur in bacterial cells in addition to the single main circle of DNA, the genosphore. Plasmids can be used as vectors to move pieces of DNA between organisms.
Explain the process of DNA replication?
- DNA is unzipped bu helicase.
- The polymerse attaches the complimantary base pairs.
- The ligase forms the strain.
- The MRNA travels through the cytoplasm to the ribosome, were the TRNA attaches amino acids in the sequence the MRNA asks for.
What are codons?
Sequences of 3 nuceotide bases, known as triplets, which occur in linear arrays on messenger DNA.