ScienceA Section 3-4 Flashcards
What is DNA? (what it stands for, where it is found, who discovered it, what its composed of and how they combine)
DNA stands for Deoxyribonucleic acid- is the molecule that contains the genetic code of organisms found in the nucleus. DNA is in each cell in the organism and tells cells what proteins to make. Mostly, these proteins are enzymes. DNA is inherited by children from their parents. This is why children share traits with their parents, such as skin, hair and eye color. (acts as a blueprint)
Found in nucleoli- responsible for for storing information and passing it on
Scientist Oswald Avery discovered DNA, Watson and Crick discovered the structure of DNA
A DNA molecule is like a ladder, its composed of adenine, guanine, thymine, and cytosine. (A + T go together, G + C go together.
(A molecule that contains the genetic code of organisms found in the nucleus. Oswald Avery discovered this. Composed of Adenine, Guanine, Thymine, and Cytosine (A+ T go together, G +C). DNA is inherited by children from their parents like eye color, hair (Acts as a blueprint).)
Chromosomes (what they are, how many in humans, gametes)
To fit large amounts of DNA into their cells, its arranged into packages (chromosomes), it contains all the genes. Each human cell nucleus contains 46 chromosomes (we have a complete set of 46). Chromosomes are organized into pairs (we have 23 pairs)
(fits lots of DNA in cells and organizes it into packages and contains all the genes.)
Genes
Genes are responsible for the inheritance of an organisms characteristic features. a single gene is and uninterrupted segment of DNA.
-Genes are located on the chromosomes and come in pairs
(are responsible for the inheritance of an organisms characteristic features. located in packages)
Alleles
variation in the DNA sequence in genes, offsprings inherit genes from both parents. They are possible forms of the same genes and differ from one another in their exact DNA sequence.
(Dont memorize this, its just so that you understand: An allele is one of a pair of genes that appear at a particular location on a particular chromosome and control the same characteristic, such as blood type or color blindness. Alleles are also called alleleomorphs. Your blood type is determined by the alleles you inherited from your parents.) \
(brings out variation and genes from parents and differ from one allele to the other).
Fertilization
The process of combining the male gamete, or sperm, with the female gamete. The product of fertilization is a cell called a zygote.
Gametes (what they are, how they work, what they are composed of)
a cell that has one role, to join with another gamete during reproduction (sex cells). male gametes are called sperm cells, females are egg cells. A gamete must contain only one copy of each different chromosome and to do this cells must divide twice. (one gamete contains 23 chromosomes). (relies on the union of 2 specialized cells).
Zygote
the cell created by the joining of the 2 gametes (is the first cell of a new individual and it then divides into 2 cells)
Embryo
created after the gametes come together and the zygote splits.
Mitosis- where it occurs, how many chromosomes are at the end of the process in humans, what this process is used for, how many times the cell divides (how many daughter cells are produced).
The process that produces two new cells with the same number of chromosomes is called mitosis. Its responsible for growth repair/regeneration. Mitosis occurs in the body cells of multicellular organisms. Once mitosis is complete, the cell has two groups of 46 chromosomes, each enclosed with their own nuclear membrane. The cell then splits in two by a process called cytokinesis, creating two clones of the original cell. (mitosis is 1 cell division).
Meiosis- where it occurs, how many chromosomes are at the end of the process in humans, what this process is used for, how many times the cell divides (how many daughter cells are produced).
Meiosis is a type of cell division that produces cells with only half the DNA of a normal cell. Because each gamete has only half the DNA of a normal cell, when the male and female unite, the zygote has a complete set of DNA. Meiosis involves 2 cell divisions. Meiosis occurs in the sex cells, so the sperm and egg cells in the human body, to create even more of themselves.
On the other side, during meiosis I, same as mitosis, they are split into 2 cells, each of which has 46 chromosomes (46 sister chromatids in total). So, during meiosis II, these 2 cells was split again into 4 cells, each of which has 23 chromosomes (23 sister chromatids in total).
Meiosis is used in sex cells. Its goal is to make daughter cells with exactly half as many chromosomes as the starting cell.
Hybrid
Hybrid just means having a combination of two different alleles (the ‘letters’ meaning either dominant or recessive). The genotype of a hybrid wild have one capital letter and one lowercase letter, like “Bb”. The organism would still possess the dominant trait, like black hair in the cats in many of our textbook examples, but it would be able to pass on a recessive trait to it’s offspring.
A Hybrid trait is also called Heterozygous.
Purebred
Purbred - a breeder who wishes to produce white cats should choose purepred parents (cats whose ancestors have produced only white offspring of several generations
Punnett squares – how to determine offspring
go from top to side, pure bred is 2 of the letters on top or the two big letters and hybrid is one big letter on top and one big on side. Big letter always comes first.
Recessive Trait
A recessive trait appears in the offspring only if 2 recessive alleles are inherited. Recessive traits can be carried in a person’s genes without appearing in that person.
Dominant Trait
Dominant: A genetic trait is considered dominant if it is expressed in a person who has only one copy of that gene … A dominant trait is opposed to a recessive trait which is expressed only when two copies of the gene are present.
Incomplete Dominance
Incomplete dominance is when a dominant allele, or form of a gene, does not completely mask the effects of a recessive allele, and the organism’s resulting physical appearance shows a blending of both alleles. (EX, a red and white rose unite - a pink rose is created)
Remember the organism chart-
it goes same number 2x then spilts then back to same number then spilts
EX 46,46, 23, 46, 23
Heterozygous
Possessing 2 different forms of a particular gene
Homozygous
the possession of 2 identical copies of the same genes
Binary fission
Binary Fission: One celled organism split into two
3 things that reduce biological diversity
- the extinction of some species
- the decrease in population of other species
- the degradation of ecosystems
Extinction - give an example
The disappearance of every individual of a species from an entire planet. Ex. dinosaurs
Define Extirpation and give expample
Local extinction or disappearance of a species from a particular area. Ex. greater prairie chicken
What human activities cause extinction and extripation?
Over hunting, habitat destruction, introduction of non-naitive species
Natural causes of extinction and extripation?
Disease, lack of food, catastrophic events (natural causes) Overspecialization
Define artificial selection
the process of selecting and breading individuals with desired traits to produce offspring with the desired traits
What is biotechnology? Explain the risks
the use of living things to make agricultural, industrial or medical products. The risk in animals having too many of the same herds could lead to disease or unsuccessful. In plants, some plants may become resistant to herbicides.
What is cloning? and examples
Creating an identical copy of entire organism, or of its cells/genes. Ex. taking a cutting from a plant, and growing an identical plant from that. and by removing a cell from a plant that has traits that are wanted.
What is artificial reproductive technology?
method of joining a male and female gamete.
What is artificial insemination?
sperms are harvested from a bowl with desired characteristics and inserted into many female cows.
What is in-vitro fertilization?
sperm and eggs from a female and male prized cows are placed in a petri dish and fertilized.
What is genetic engineering? Explain how it works
refers to any technology that involves altering the DNA of an organism. It works by removing a gene from one organism and inserting it into another.
What is in-situ conservation?
refers to the maintenance of populations of wild organisms in their ecosystems. Ex national park or duck unlimited
What is ex-situ conservation?
the maintenance of organisms outside of their ecosystems or natural habitats. Ex endangered species maintained in a zoo
What are strategies to conserve biological diversity?
Protected areas:-government creates laws to protect habitat, orgs work to provide habitat
Restoration of ecosystems and species: - programs are created, try to reintegrate, close to extinct animals and exotic plants.
Resource use policies
Controlling the spread of exotic species - ultimately depends on the acts of individuals
Conservation of genetic resources: - seed banks, egg banks, and zoos in case something goes extinct and this is done with ex-situ conservation
A seed bank is an example of
conservation of plant genetic resources
What is the difference between mitosis and meiosis
Mitosis gives identical cells to each other and to the mother cell, while meiosis leads to genetic variation due to crossing over and independent assortment. Mitosis includes one division , while meiosis includes two. Mitosis is used in growth repair and meiosis is the development of sex cells.
How many chromosomes are in a gamete and why is it important to have these chromosomes
theres 23. In this way, when an egg and sperm cell combine during fertilization, the resulting embryo will inherit the appropriate amount of unique genetic information from each parent. And won’t carry a disorder of some sort.
