Genetics Test Flashcards
What is genetics?
scientific study of heredity
What is fertilization?
the action or process of fertilizing an egg, female animal, or plant, involving the fusion of male and female gametes to form a zygote.
What is true-breeding?
term used to describe organisms that produce offspring identical to themselves if allowed to self-pollinate.
what is a trait?
specific characteristic that varies from one individual to another
What is a hybrid?
offspring of crosses between parents with different traits.
What is a gene?
sequence of DNA that codes for a protein and thus determines a trait.
What is an allele?
one of a number of different forms of a gene
what is a gamete?
specialized cell involved in sexual reproduction
What does homozygous mean?
term used to refer to an organism that has two identical alleles for a particular trait.
what does heterozygous mean?
term used to refer to an organism that has two different alleles for the same trait
What is a phenotype?
physical characteristics of an organsim
genotype
genetic makeup of an organism
independent assortment
independent segregation of genes during the formation of gametes
incomplete dominance
situation in which one allele is not completely dominant over another
codominance
situation in which both alleles of a gene contribute to the phenotype of the organism
multiple alleles
three or more alleles of the same gene
polygenic traits
traits controlled by two or more genes
gene map
diagram showing the relative locations of each known gene on a particular chromosomes
transformation
process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria
transcription
process in which part of the nucleotide sequence of DNA is copied into a complementary strand of RNA
translation
decoding of a mRNA message into a polypeptide chain
intron
sequence of DNA that is not involved in coding for a protein
exon
expressed sequence of Dna; codes for a protein
codon
three nucleotide sequence on messenger RNA that codes for a single amino acid
anticodon
group of three bases on a tRNA molecule that are complementary to an mRNA codon
mutation
change in DNA sequence that affects genetic information
What did Gregor Mendel do?
he worked with peas, wanting to cross pollinating them to see what traits would appear in the offspring
hybrid
the offspring of crosses between parents with different traits
what did Mendel conclude?
From these experiments, Mendel concluded that some alleles are dominant and others are recessive.
What is the principle of dominance?
some alleles are dominant and others are recessive.
What is segregation?
during gamete formation, alleles segregate from each other so that each gamete carries only a single copy of each gene.
What did each F1 plant produce?
two types of gametes-those with the allele for tallness and one for shortness.
What are the principle of probability used for?
to predict the outcomes of genetic crosses
what is probability
the likelihood that a particular event will occur is called
what can punnett squares be used for
to predict and compare the genetic variations that will result from a cross
what is the principle of indepedent assortment?
states that genes for different traits can segregate independently during the formation of gametes. Independent assortment helps account for the many genetic variations observed in plants, animals, and other organisms.
Give a summary of Mendel’s Principles:
- The inheritance of biological characteristics is determined by individual units known as genes. Genes are passed from parents to their offspring.
- In cases in which two or more forms (alleles) of the gene for a single trait exist, some forms of the gene may be dominant and others may be recessive.
- In most sexually reproducing organisms, each adult has two copies of each gene-one from each parent. These genes are segregated from each other when gametes are formed.
- The alleles for different genes usually segregate independently of one another.
True or False: Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes.
True
Why did Thomas Hunt Morgan chose fruit flies?
they were small, easy to keep in a labratory, and able to produce large numbers of offspring in a short period of time.
What assorts independently?
the chromosomes
What did Frederick Griffith want to learn?
how bacteria makes people sick. He wanted to learn how certain types of bacteria produce a serious lung disease known as pneumonia.
What did Avery learn?
the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next.
what is a bacteriophage?
a kind of virus that infects bacteria
What did Hershey and Chase conclude?
the genetic material of the bacteriophage was DNA, not protein.
what are the purines?
adenine and guanine
what are the pyrimidines?
cytosine and thymine
What was Watson and Crick’s model of DNA?
a double helix
_____ is a double helix in which two strands ae wound around each other.
DNA
What are histones?
dna that is tightly coiled around proteins
what happens during DNA replication?
te DNA molecule separates into two strands, and then produces two new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template, or model, for the new strand.
what does DNA polymerase do?
joins individual nucleotides to produce a DNA molecule, which is, of course, a polymer.
What are the three main types of RNA?
messenger RNA, ribosomal RNA, and transfer RNA.
what does messenger RNA do?
carries copies of the instructions for assembling amino acids into proteins
what is ribosomal RNA
makes up ribosomes , proteins also make up ribosomes
what does transfer RNA do?
transfers each amino acid to the ribosome as it is specified by coded messages in mRNA
what does RNA polymerase do?
during transcription, RNA polymerase binds to DNA and separates the DNA strands. RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA.
what are promoters?
signals in DNA that indicate to the enzyme where to bind to make RNA.
What happens during translation?
the cell uses information from messenger RNA to produce proteins
what is the first step of translation?
messenger RNA is transcribed in the nucleus, and then enters the cytoplasm and attaches to a ribosome
what is the second step of translation?
translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds to methionine. The ribosome also binds the next codon and its anticodon.
what is the third step of translation?
the ribosome joins the two amino acids-methionine and phenylalanine-and breaks the bond between methionine and its tRNA. The tRNA floats away from the ribosome, allowing the ribosome to bind another tRNA. The ribosome moves along the mRNA, binding new tRNA molecules and amino acids.
what is the fourth step of translation?
the process continues until the ribosome reaches one of the three stop codons. The result is a complete polypeptide.
What are mutations
changes in genetic matrial
what are point mutations
gene mutations involving changes in one or a few nucleotides
what are frameshift mutations
if a nucleotide is added or deleted, the bases are still read in groups of three, but now those groupings are shifted for every codon that follows
what is polyploidy
the condition in which an organism has extra sets of chromosomes
what is an operon
a group of genes that operate together
what is the lac operon
the genes that need to be expressed in order for the baterium to be able to use the sugar lactose as a food
what turns the lac genes on?
by repressors
what turns the lac genes off
by the prescense of lactose
Do most eukaryotes have operons?
no
how are eukaryotic genes controlled?
individually and have regulatory seqeunces that are much more complex than those of the lac operon.
what is differentiation?
specialized in structure and function
what are hox genes
control the differentiation of cells and tissues in the embryo. a mutation in one of these master control genes can completely change the organs that develop in specific parts of the body.
explain what dominant and recessive mean in terms of alleles
an organism with a dominant allele for a particular form of a trait will always exhibit that form of the trait.
an organism with a recessive allele for a particular trait will exhibit that trait only when no dominant allele is present.
what is the difference between diploid and haploid
a cell that contains both sets of homologous chromosomes is said to be diploid. The gametes of sexually reproducing organisms contain only a single set of genes. They are said to be haploid.
what process produces gametes
meiosis
describe a nucleotide
units that make up DNA. Made up of three basic components: a 5-carbon sugar called deoxyribose, a phosphate group, and a nitrogenous base
what are the functions of DNA and RNA polymerase
RNA polymerase-binds to DNA and separates the DNA strands. It then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA.
DNA polymerase- joins individual nucleotides to produce a DNA molecule.
