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.
