Flashcards in Genetics Deck (59)
Repeating sequence of events in the life cycle of a dividing cell.
What are the four stages of the cell cycle?
G1: growth and metabolism.
S: synthesis of DNA.
G2: growth and metabolism.
What are the three stages of interphase?
G1, S, G2.
What is the major difference between cells in G1 vs G2?
Cells in the G2 stage have twice as much genetic material (DNA) as those in G1.
What is Mitosis?
Nuclear division usually followed by cytoplasmic division that forms two genetically identical daughter cells.
What are the four phases of mitosis?
What is prophase?
Chromatin condenses into distinct chromosomes. The nuclear membrane disintegrates, and spindles form at opposite ends of the cell.
What is Metaphase?
Chromosomes align on a plane that is equally distant from both spindles.
What is anaphase?
The paired chromosomes move to opposite ends of the cell.
What is telophase?
Chromosomes are grouped in separate new nuclei in the emerging daughter cells. At the end of mitosis, two cells with identical genetic material have been produced.
What is a gene?
Section of DNA that codes for a specific protein.
Genes are arrange lengthwise on the chromosome
What are homologous chromosomes?
Chromosomes that occur in pairs; they are the same length and have alleles for the same traits at corresponding locations.
What does Haploid mean?
A cell that contains only one chromosome from each homologous pair.
What is diploid?
A cell that contains a pair of each homologous chromosome; on set is inherited from each parent.
Examples: body cell, fertised egg
What is a primary sex cell?
A cell contained in the gonads that will eventually become a gamete.
What is meiosis?
Cell division that produces haploid gametes from diploid cells. Usually four gametes are formed from one diploid cell.
Contrast spermatogenesis with oogenesis.
Spermatogenesis: the production of sperm cells.
Oogenesis: the production of egg cells. usually only one egg is formed from one diploid cell.
What is a polar body?
Small, non-functioning cell produced as a result of oogenesis (egg formation)
Summarize the work of Gregor Mendel?
A 19th century monk who studied heredity in garden pea plants, he published the first genetic studies and was known as the "father of genetics".
What is Mendel's Law of Dominance?
When orgaanisms that are pure breeds for contrasting traits are crossed, the trait expressed by the offspring is the dominant trait.
What is menel's Law of Segregation?
Modern form: during meisosis, homologous chromosomes (with the alleles they carry) separate and go to different gamete cells.
What are Alleles?
One of two or more different forms of a gene?
What does homozygous meant?
Having two identical alleles for a trait.
Examples BB, bb
What does heterozygous?
having two different alleles for a trait.
What does Genotype mean?
The genetic make-up of an organism; the actual genes an organism has for a trait.
Example: a cat with a brown-eyed phenotype may have a heterozygous genotype (one allele for brown, one allele for blue.
What is a phenotype?
The expression of a genotype; can be an appearance or a function of an organism.
Examples: tall, blue eyes, type B blood.
What is Mendel's Law of Independent Assortment?
Modern Form: the inheritance of alleles on one homologous chromosome pair has no effect on the inheritance of alleles on a different homologous chromosome pair.
Summarise the work of Thomas Hunt Morgan?
received the Nobel Prize for research on a fruit fly. He located certain genes on the chromosomes; discovered X-linked genes.
What does linkage mean?
Genes that are inherited together because they are located on the same chromosome; they do not independently.