bio Flashcards
meiosis
- only happens when producing female/male gametes
- cell divides twice to produce 4 different daughter cells
- all cells haploid (half the # of chromosomes)
- offspring are all genetically different
prophase I: nuclear membrane disappears, DNA condenses and homologous chromosomes start to pair up
metaphase I: homologous chromosomes move together to the middle and line up. crossing over takes place and promotes genetic diversity
anaphase I: chromosomes separate
telophase I: 2 nuclei form, each nucleus contains copy of DNA
prophase II: nuclear membrane disappears, DNA exists as chromosomes
metaphase II: line up in the middle
anaphase II: split to each hole, chromatids split
telophase II:4 nuclei form, cell divides, forming 4 new cells
independent assortment
2 equally probable arrangements of chromosomes in metaphase I that results in 4 different daughter cells
biotechnology and its advantages/disadvantages
the use of technology and organisms to produce useful products. produces useful products. raises ethical problems
cloning
process that produces identical copies of genes, cells or organisms
gene cloning
manipulating DNA to produce multiple copies of a gene or another segment of DNA in foreign cells. Used for further studying or mass producing the protein that the gene codes for.
steps of cloning a gene
1) choose a vector to be used as a carrier of the DNA to be cloned (i.e. plasmid)
- a plasmid is a small, circular piece of DNA in a bacterial cell
2) insert a segment of DNA to clone into the vector
- this DNA molecule that has genetic material from a different source is called recombinant DNA
3) introduce the recombinant DNA into foreign cells through transformation.
- once inside the foreign cells, multiple copies of the cloned gene will be made.
transgenic organisms
organisms that have foreign DNA from a different species inserted into them. We should be concerned because 1) the use of herbicide-resistant plants can lead to the use of stronger herbicides that will leak into the soil and water systems 2) genes can cross to other species 3) GMOs may out-compete species in the wild 4) long-term effects of GMOs are not known 5) GMOs may produce allergic reactions 6) GMO products do not have labels on them 7) a lot of money is spent on genetic research 8) private companies have too much say over the global food market 9) ethics behind using other species for our own benefit.
purposes of transgenic plants and transgenic animals
transgenic plants: increases vitamin intake, reduces malnutrition, increases crop yield and taste. transgenic animals: used to produce human growth hormones or anti clotting factors, may be used as organ donors for humans
artificial insemination
a process that involves collecting and concentrating sperm, and then placing it in the female’s uterus
in vitro fertilization (IVF)
process that results in a female’s eggs being fertilized by sperm outside the body
gene therapy and concerns
an experimental treatment to cure genetic disorders that involve inserting a healthy normal form of a gene into cells of tissues that are affected by a disorder. some people have experienced negative effects with gene therapy, and safer procedures need to be developed.
GMOs
organisms that have foreign DNA from a different species inserted into them.
mutation
permanent change in the genetic material of an organism. they can occur during DNA replication, or as a result of environmental agents such as UV rays, and introduce changes to DNA, resulting in the change of a trait. some mutations can be harmful and cause a cell to die, malfunction, or multiply uncontrollably. some mutations can be positive, or have no effect. E.g. if a bee is mutated so that it has no wings, it’s hard for bees to gather pollen. if bees are given an extra set of legs, it could be helpful. some mutations have no effect on them though.
natural selection
favours traits that make an individual better-suited for its environment, as the population changes since individuals with favourable characteristics survive and reproduce.it’s situational, as a trait that may be a disadvantage to an individual at one time may be advantageous to its survival later.
adaptation
structural or behavioural feature or physiological process that improves the organism’s chance of surviving in its environment to reproduce. it’s important as organisms that have an advantageous mutation may survive better in a changing environment
adaptive radiation
the diversification of a common ancestral species into a variety of differently adapted species. Darwin’s finches are an example because they started off as 1 specie, but due to selective pressure, they broke off into new species
extinction
occurs when a species completely disappears from earth, often due to selective pressure
mutagen
a substance or event that increases the rate of mutation. physical mutagens cause physical changes to the structure of DNA. eg x-rays, UV radiation, chemical mutagens are molecules that can enter the nucleus of a cell and chemically react with DNA. e.g. nitrites, and gas fumes
carcinogen
substance or agent that causes cancer. it increases the risk of developing cancer. e.g. processed foods, cigarettes, cosmetics, bacteria, BBQ, viruses, and cleaning products
artificial selection and benefits and risks
selective pressure exerted by humans on populations in order to improve or modify desirable traits. benefits: we can breed animals that produce more (example: milk), have more meat, and we can breed crops to resist disease, drought and insect infestations. eg/ through selective pressure, the wild mustard plant is used to produce 6 plants. risks: some selectively bred animals have health problems (English bulldogs have respiratory problems). selectively bred plants lack genetic diversity because they are all similar
biodiversity
exists at 3 levels: species diversity, genetic diversity, and ecosystem diversity. species diversity: variety and abundance of species in a given area. genetic diversity: variety of inherited traits within a species. ecosystem diversity: variety of ecosystems in the biosphere. variations in genes is related to all 3 types of biodiversity, as it allows for changes among us. diversity in genes makes us all different.
genetics
field of biology that studies heredity, or the passing of traits from parent to offspring
Gregor mendel
discovered how traits are inherited by experimenting on pea plants (because they were easy to grow and able to self-fertilize). he used true-breeding pea plants that produce offspring with only 1 form of a trait. parent plants produced new plants called offspring in the first generation (F1). Plants from the first generation were allowed to self-fertilize to produce offspring in the second generation (F2). He discovered that when 2 different true-breeding pea plants are crossed, trait disappears in the F1 offspring. based on this observation , he proposed that each plant has 2 factors for a trait, each parent gives 1 factor for each trait, 1 factor dominates over the other if present, and the “factors” he referred to in his conclusion are what we call alleles
species
group of organisms that can interbreed in nature and produce fertile offspring
allele
one of the forms of a gene. e.g. the gene for eye colour has many variations (alleles) such as an allele for blue eyes.
gene
stretch of DNA or RNA that determines a certain trait, and mutates to take different forms
law of segregation
states that alleles for a trait separate during meiosis. each gamete carries 1 allele for each trait. during fertilization, each gamete contributes an allele for each trait.
how/when are dominant/recessive alleles expressed
alleles that are dominant will always be expressed if present, and are represented with a capital letter. alleles that re recessive will only be expressed if there are 2 recessive alleles, and are represented with lower case letters.
genotype
specific combination of alleles an organism has for a specific trait
phenotype
physical description of an organism’s trait
homozygous
organism with 2 of the same alleles for a particular trait
heterozygous
organism with 2 different alleles for a particular trait
codominance and examples
the condition in which both alleles for a trait are equally expressed in a heterozygote; both alleles are dominant/ HRHW. examples are a red cow mates with a white bull to produce roan offspring. sickle cell anemia-genetic disorder, where the red-blood cell is c-shaped (sickle) and cannot transport oxygen properly.
incomplete dominance
condition in which neither allele for a gene completely conceals the presence of the other; results in intermediate expression of a trait. when red (CRCR) flowers are white (CWCW) flowers of the 4’O clock flowers are crossed, the resulting offspring have an intermediate phenotype, pink flowers (CRCW). all 3 phenotypes are observed in the F2 generation.
sex-linked traits
traits controlled by genes on sex chromosomes. XB is normal, Xb is affected, and Y is Y chromosome.
invasive species
a specie that is not native to an ecosystem and can cause harm to it, like Asian long-horned beetles, Asian gypsy moths
how are genes involved in the process of protein production
sequence of bases in DNA’s genetic code will determine the sequence of bases on a strand of RNA, which in turn will determine the sequence of amino acids needed to make a protein
karyotype
a photo of pairs of homologous chromosomes in a cell. it reveals the gender of a fetus, and whether they have a genetic disorder or not. if there are 2 X chromosomes in the 23rd pair, it’s a female. if there is 1 x and 1 Y chromosome in the 23rd pair, it’s a male.
homologous chromosome
chromosome that contains the same sequence of genes as another chromosome. they’re NOT identical to each other
autosomes
the first 22 pairs of chromosomes
sex chromosomes
the 23rd pair chromosome. determines sex of the fetus
how are chromosomes arranged and numbered in a karyotype
in order of their length, from longest to shortest, sex chromosomes are last
chromosome
a threadlike structure of nucleic acids and proteins carrying genetic information in the form of genes
chromatin
condenses completely to form a chromosome
DNA
all of the genetic information
how is structure of DNA related to passing on genetic information
the sequence of bases in a DNA molecule determines the specific sequence of amino acids in a protein molecule
structure of DNA
nucleotides are the basic building blocks of nucleic acids, which are DNA and RNA. nucleotides consist of 3 components: a phosphate group, a sugar and a nitrogenous base. nitrogenous bases in DNA are adenine and thymine, and cytosine and guanine. a DNA molecule has 2 strands of nucleotides, twisted ladder (double helix) structure, sides of the ladder is made up of sugar and phosphate groups, and rungs of the ladder are made up of 2 nitrogenous bases held together by hydrogen bonds.
what are the complementary bases
adenine and thymine (double bond), and cytosine and guanine (triple bond)
main function of DNA
instructions provided by DNA are responsible for the development of an organism and the function of all its parts
genome
the complete DNA sequence in each cell of an organism
population
members of the same species living in the same geographical area at the same time
trait
an inherited characteristic, such as eye colour or hair colour
selective advantage
a genetic advantage that improves an organism’s chance of survival, usually in a changing environment
monoculture
repeated planting of the same varieties of a species over large expanses of land
protein
an organic chemical composed of a chain of building-block molecules called amino acids
