Exam 3 Flashcards
Who was Gregor Mendel?
Gregor Mendel was the first person to analyze the patterns of heredity and deduced the fundamental principles of genetics.
Developed his theory by working with pea plants.
What is Mendel’s theory of segregation?
Gametes carry only one allele for each inherited character.
- The two alleles for a character segregate from each otherduring the production of gametes.
What is a gene?
A portion of a DNA molecule that serves as the basic unit of heredity. Genes control the characteristics that an offspring will have by transmitting information in the sequence of nucleotides on short sections of DNA.
What is a locus?
A gene locus is a specific location of a gene along a chromosome.
What is an allele?
The alternative versions of genes (brown v blue eye color)
What do the terms “homozygous” and “heterozygous” refer to?
“Heterozygous” would mean there is both a dominant and recessive allele for a character. The dominant allele would manifest in the phenotype.
“Homozygous” would mean there are two of the same alleles. Either homozygous dominant (PP) or homozygous recessive (pp) depending on the trait.
An organism must be homozygous recessive for a recessive trait to manifest in the organism’s phenotype.
What are the definitions of genotype and phenotype?
Genotype is the actual allele combinations for a trait.
Phenotype is the physical manifestation of a trait.
If the phenotype of a character is the dominant trait, it could be either homozygous dominant or heterozygous. If the phenotype is the recessive trait then it can only be homozygous recessive.
What is a monohybrid cross? Know how to set up a punnett square and be able to explain the outcome for the F1 and F2 generations both in terms of genotype and phenotype.
A monohybrid cross is a chart that shows all genotype possibilities for a character based on the inherited traits. “Mono” means one so it’s only tracking one character.
What is a test cross? Why is it performed? Know the results if the test organism is homozygous dominant or heterozygous.
In genetics, a test cross, first introduced by Gregor Mendel, involves the breeding of an individual with a phenotypically recessive individual, in order to determine the zygosity of the former by analyzing proportions of offspring phenotypes. Zygosity can either be heterozygous or homozygous.
What is a dihybrid cross? Be able to set up a punnett square and explain the outcome for the F1 in terms of genotype and phenotype.
A dihybrid cross is a chart which predicts possible outcomes, however unlike the monohybrid cross, the dihybrid cross compares two characters (ie hair and eye color).
What is the purpose of a punnett square?
To predict possible genotypes of offspring.
What is independent assortment?
The inheritance of one character has no effect on the inheritance of another. (Not all blondes have blue eyes and not all brunettes have brown eyes).
Understand the ABO blood system. Be able to work through a genetic problem that involves blood type.
Blood type is inherited like any other trait. A parent donates one allele for blood type and the two alleles together are the blood type.
How is gender determined?
Both parents donate one sex chromosome. Since women are XX, they can only donate an X chromosome. However, since men are XY they can donate either an X or Y chromosome. If the male donates an X, the zygote will be female. If he donates a Y the zygote will be male. There are exceptions due to mutations.
What are X-linked traits? Be able to work through a genetic problem that involves x-linked trait such as colorblindness.
Sex linked traits are alleles, but because they’re carried on a sex chromosome (usually X because it’s much larger), we track them using superscript.
What is a mutation?
A gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people. Mutations range in size; they can affect anywhere from a single DNA building block (base pair) to a large segment of a chromosome that includes multiple genes.
Mutations are the most common way for new phenotypes to arise.
Name two nucleic acids?
DNA and RNA.
Where is DNA located in eukaryotic cells? In prokaryotic cells?
In prokaryotic cells, the DNA is located in the nucleoid.
In eukaryotic cells, the DNA is located in the nucleus.
Describe the structure of DNA.
DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base.
The four types of nitrogen bases are:
- Adenine (A)
- Thymine (T)
- Guanine (G)
- Cytosine (C)
Which individuals contributed to our understanding of DNA structure?
Watson and Crick proposed that DNA is a double helix.
Rosalind Franklin was the first to examine DNA fibers.
Maurice Wilkins was the weasel who took credit for Franklin’s discovery.
What are nucleotides? Be certain you know the components, and how they come together to form DNA.
The four nucleotides found in DNA differ in their nitrogenous bases. These bases are:
- Thymine (T)
- Cytosine (C)
- Adenine (A)
- Guanine (G).
A pairs with T and C pairs with G (AT, CG)
*RNA has uracil (U) in place of thymine (T). A pairs with U and C pairs with G (AU, CG)
What are complementary base pairing rules?
Write the complement to the following strand:
ATC-CGA-TTA-CGA-TGA
A bonds with T and C bonds with G.
ATC-CGA-TTA-CGA-TGA
TAG-GCT-AAT-GCT-ACA
In RNA, T is replaced with U.
ATC-CGA-TTA-CGA-TGA
UAG-GCU-AAU-GCU-ACU
What type of bond joins the nitrogen bases?
Hyodrogen bonds.
What is DNA replication?
Why does DNA replicate?
DNA Replication:
The dna strand is split apart and each half is paired with the corresponding nitrogenious bases to create two identical strands, each with half of the parent strand.
DNA polymerases are a family of enzymes that carry out all forms of DNA replication.
Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. There are DNA and RNA helicases. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.
DNA replicates so that it can be transfered to new cells when the cells split.
Which molecules are referred to as the code, codon, and anti-codon?
mRNA (messenger RNA): contains codons that codefor the peptide sequence.
tRNA (transfer RNA): contains the anticodon on the “tip” and the corresponding amino acid on the “tail”. Link the correct amino acid to its corresponding mRNA codonthrough codon-anticodon interaction.
What is RNA? How does it differ from DNA structurally?
DNA: Long-term storage of genetic information; transmission of genetic information to make other cells and new organisms.
RNA: Used to transfer the genetic code from the nucleus to the ribosomes to make proteins. RNA is used to transmit genetic information in some organisms and may have been the molecule used to store genetic blueprints in primitive organisms.
What is the product of transcription? Where does this take place? Can you describe the process?
RNA uses DNA as a template to make an RNA molecule. RNA then leaves the nucleus and goes to a ribosome in the cytoplasm, where translation occurs.
What occurs in translation? What is the product of translation? Where in the cell does this occur?
Translation is the final step on the way from DNA to protein. It is the synthesis of proteins directed by a mRNA template. The information contained in the nucleotide sequence of the mRNA is read as three letter words (triplets), called codons. Each word stands for one amino acid.
This occurs on the surface of ribosomes.
Know the terms associated with bacterial shape.
