Biology test 5
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What are characters in genetics?
Different heritable features, such as flower color
What are traits in genetics?
Character variants, such as purple or white flower color
What are the advantages of using the pea plants in genetic study?
- Characters and character traits
- Mating easily controlled
- Stamens and carpel
- Cross pollination (fertilization between different plants) involves dusting one plant with the pollen of another
What are the sperm and egg producing organs in plants?
Plants that produce offspring of the same variety when they self-pollinate
Mating 2 contrasting, true-breeding varieties
True breeding parents
The offspring of the true breeding parents
The product of when the F1 generation self-pollinates or cross pollinates with another F1 hybrid
What was Mendel's term for genes?
What were some of Mendel's important discoveries?
- Factors exist in versions (alleles)
- Alleles segregate/separate (law of segregation)
- Independent assortment
- Particulate inheritance
What 3 mechanisms contribute to genetic variation?
- Independent assortment of chromosomes
- Crossing over
- Random fertilization
What factors should an experimental organism have?
- Easy to culture (small size; minimal nutrient requirements)
- Quick generation time
- Simple genetics
- Mutant form apparent
- Economic importance
Discreet expression or form, 1 among several, for a given character.
Individuals that are heterozygous for one character
Heterozygous for both traits
Law of Segregation
the two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes
Law of Independent Assortment
- •each pair of alleles segregates
- independently of each other pair of alleles during gamete formation
Inheritance of characters by a single gene may deviate from simple Mendelian patterns in certain situations such as
- When alleles are not completely dominant or recessive
- More than one allele
- When a gene produces multiple phenotypes
occurs when phenotypes of the heterozygote and dominant homozygote are identical
the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties
two dominant alleles affect the phenotype in separate, distinguishable ways
an additive effect of two or more genes on a single phenotype
Chromosome Theory of Inheritance
–Mendelian genes have specific loci (positions) on chromosomes
–Chromosomes undergo segregation and independent assortment
Wild type phenotype
the most commonly occurring phenotype in nature
How do you create an F2 generation?
Cross the F1 generation with itself
Types of linkages
- Two traits on same chromosome
- sex-linkage: a trait that is linked on a sex chromosome
What is the SRY gene's function?
On Y chromosomes, code for male anatomical parts
For a recessive X-linked trait to be expressed...
- Female needs two copies of the alleles (heterozygous)
- Male needs one copy of the alleles (hemizygous)
offspring with same phenotypical traits as the parents
Offspring with phenotypical traits different from parents
Some of the DNA that is replicated is the old strand and some is new
Enzyme that prevents supercoiling by cutting DNA and then reconnecting it
Single stranded binding proteins (SSBP)
Protects DNA while in single stranded state
Each fragment on a lagging strand
Used to make proteins
Origins of replication
Where the two DNA strands are separated, opening a replication bubble
An enzyme that starts an RNA chain from scratch and adds RNA nucleotides one at a time using the parental DNA template
Joins together Okazaki fragments
Stretch of DNA that is transcribed
Three stages of transcription
Carried by tRNA. Base pairs with a complementary codon on mRNA
Y shaped region where new DNA strands are elongating
synthesizes a leading strand continuously, moving toward the replication fork
Short nucleotide strand where the 3' end serves as the starting point for a new DNA strand
The process by which DNA directs protein synthesis in transcription and translation
The synthesis of RNA under the direction of DNA
Synthesis of polypeptide using information in the mRNA
Site of translation
The initial RNA transcript from any gene prior to processing
- Concept that cells are governed by a cellular chain of command:
- DNA -> RNA -> protein
One of the two DNA strands that provides a template for ordering the sequence of complementary nucleotides in a RNA transcript
Pries the DNA strands apart and hooks together the RNA nucleotides
The DNA sequence where the RNA polymerase attaches
Sequence signaling the end of transcription
When enzymes in the eukaryotic nucleus modify pre-mRNA before the genetic messages are dispatched to the cytoplasm
During RNA processing, has is pre-mRNA modified?
The 5' end gets 5' cap and the 3' end gets a poly-A tail
What are the functions of the 5' cap and the poly-A tail?
- Facilitate the export of mRNA
- Protect mRNA from hydrolytic enzymes
- Help ribosomes attach to 5' end
Non-coding sequences in RNA
Regions that are eventually expressed and translated into amino acid sequences
Removes introns and joins exons
Consist of a variety of proteins and several small ribonucleoproteins (snRNPs) that recognize splice sites
What are the three binding sites for tRNA on a ribosome and what are their functions?
- P site: holds the tRNA that carries the growing polypeptide chain
- A site: holds the tRNA that carries the next amino acid to be added to the chain
- E site: exit site where discharged tRNAs leave the ribosome
Nucleotide pair substitution
Replaces one nucleotide and its partner with another pair of nucleotides
Have no effect on the amino acid produced by a codon because of redundancy in the genetic code
Still code for an amino acid, but not the correct amino acide
Change an amino acid codon into a stop codon nearly always leading to a nonfunctional protein
Insertion or deletion of nucleotides may alter the reading frame, producing a...
Physical or chemical agents that can cause mutations
When did Darwin publish Origin of Species?
Scale on which organisms were arranged by Aristotle when they were thought to be static
Organisms are molded by catastrophe
Mechanisms of change are constant over time, such as weathering/erosion, sedimentation, subsidence/uplift
Similarity coming from common ancestry
Anatomical resemblances that represent variations on a structural theme present in a common ancestor
Remnants of features that served important functions in the organism's ancestors
Geographic distribution of species
Species that are not found anywhere else in the world
Evolution of similar or analogous features in distantly related groups
When a species does not take the carrying capacity of its habitat into consideration so therefore produces too many offspring which then die rapidly, creating a sharp incline and decline in population
Intrinsic rate of growth
Types of fossils
- Direct (bones, tissue)
- Indirect (footprints, dung, teeth marks)
- Micro and macro (unicellular organisms)
Aspects of Natural Selection
- Variation in a population
- Phenotype/physical differences associated with differences in reproductive success (fitness)
- Populations always grow beyond the environment's capacity to support them
- Competition ensues
- Differential reproduction and survival of so-called "favored" variation
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