Exam 1: Gen Bio Review Flashcards
Describe a chromosome, its anatomy, and its various forms
-A chromosome consisting of just one chromatid is a monad. If it has two chromatids, it is a dyad.
-A chromosome is made of chromatin fibers that coil and condense
-Chromosomes are visible only during mitosis and meiosis but are always present
-Electron microscopy of chromosomes in varying states of coiling led to the folded-fiber model
Compare and contrast the similarities and differences between homologous chromosomes and sister chromatids.
Homologous chromosomes: Homologous chromosomes contain identical gene sites along their length. Each site is called a locus. (2n) They pair up during meiosis.
Sister chromatids: The sister chromatids are joined to each other via the centromere and only become separated when cell division occurs. They are identical and are created through synthesis and separated during anaphase of mitosis and anaphase 2 of meiosis.
Contrast Complete, Incomplete, and Co- Dominance
Codominance: Joint expression of both alleles in a heterozygote
Complete Dominance: Dominant allele completely expressed.
Incomplete Dominance: Intermediate phenotype. This allelic relationship led to the incorrect concept of blending inheritance.
Gene
An inherited factor (encoded in the DNA) that helps determine a characteristic
Allele
One of two or more variations of a gene
Locus
Specific place on a chromosome occupied by an allele
Genotype
Set of alleles possessed by an individual organism
Phenotype or trait
An appearance of manifestation of a characteristic
Ex: Blue eyes
Characteristics or character
An attribute or feature
Ex: Eye color
Centrosome
An organelle near the nucleus of a cell which contains the centrioles from which the spindle fibers develop in cell division.
Centrioles
-They occur in pairs perpendicular to each other
-9 triplets of microtubule arrangements
-Nontubulin proteins hold them together
Nucleolus
An amorphous component of the nucleus where ribosomal RNA (rRNA) is synthesized and where the initial stages of ribosomal assembly occur
Nucleoid
The nucleoid is an irregularly shaped region that houses genetic material. This is only found in prokaryotes.
Diploid vs haploid
Haploid cells are those that have only a single set of chromosomes while diploid cells have two sets of chromosomes.
Centromere
The contricted region of the chromosome to which kinetochores form and microtubules attach.
Eukaryotic cell characteristics
-Polysaccharide cell walls
-Methionine
-Linear chromosomes, rarely plasmids
-80S Ribosomes
Draw metacentric, submetracentric, acrocentric, and telocentric chromosomes and be able to identify where the centromere is
1) Middle
2) Between middle and end
3) Close to end
4) End
What is the function of the telomeres?
They protect the ends of chromosomes
Pseudohomologues
Behave as homologs in meiosis
Ex: X and Y
Describe the characteristics of a model organism.
-easy to grow
-cheap
-observable characteristics with two distinct forms
-high brood size
-easy to selectively breed
-single season maturation time
-true-breeding strains
-precendence
-other research showed that pea hybrids could be produced