Bio 121 Unit 2 Exam Study Guide with
Questions and Correct Answers
What is a nucleosome made of? ✅Eight histone proteins and two rounds of DNA
double helix wrapping around those eight histone proteins
What are the names of the histone proteins? ✅H2a, H2b, H3, and H4 (two of each)
What cells have a nucleosome? ✅Eukaryotic cells
What phase is interphase in? ✅mitotic phase
In what phase does DNA replication take place? ✅the S phase on interphase
Interphase takes up what percent of the cell cycle? ✅the longest time
When does the centrosome replicate (duplicate)? ✅end of G1 and the beginning of S
phase
When is the centrosome duplication complete? ✅G2
When does the nuclear membrane fragment? ✅The end of prophase (reappears at
telophase)
What is a cohesive protein? ✅holds two sister chromatids together
What is a centrosome? ✅microtubule organizing center
When is the centrosome replicated? ✅interphase
What is a centromere? ✅waist structure of duplicated chromosomes where
kinetochores are formed
What do microtubules form? ✅mitotic spindles during mitosis and meiosis
How are spindles formed? ✅a-tubulin and b-tubulin proteins (through polymerization)
What is polymerization? ✅process in which large compounds are built by joining
smaller ones together
Microtubules grow from ______ and connect to _______ ✅centrosome; kinetochore of
duplicated chromosomes
, How do sister chromatids separate? ✅by depolymerization of microtubules from the
kinetochore side and degradation of cohesion proteins
Homologous chromosomes structure ✅Chromosomes that have the same sequence
of genes and the same length
Homologous Chromosomes ✅one of two paired chromosomes, one from each parent,
that carries genes for a specific trait at the same location
Alleles ✅different forms of a gene
What do duplicated homologous chromosomes form? When? ✅Tetrads during
prophase 1
Chromatid ✅replicated chromosome
Sister chromatids ✅two chromatids of a replicated chromosome
In what cells does mitosis occur? ✅Both somatic and reproductive cells
In what cells does meiosis occur?What do they form? ✅reproductive cells and
gametes
How does a zygote divide? Forms? ✅by mitosis and forms two daughter cells which
will divide further to form a multi cell embryo
How many chromosomes are there in a human somatic cell? ✅46 chromosomes (23
pairs)
How many chromosomes in a human egg or sperm? ✅23 chromosomes
What is the difference between cytokinesis of plants and animals? ✅plants have a cell
plate and animals form cleavage furrow
What is the name for bacterial cell division? ✅binary fission
In which cells do microtubules form within the nuclear membrane? ✅fungal yeast and
protist
What protein complex holds sister chromatids together? ✅cohesin complex
Questions and Correct Answers
What is a nucleosome made of? ✅Eight histone proteins and two rounds of DNA
double helix wrapping around those eight histone proteins
What are the names of the histone proteins? ✅H2a, H2b, H3, and H4 (two of each)
What cells have a nucleosome? ✅Eukaryotic cells
What phase is interphase in? ✅mitotic phase
In what phase does DNA replication take place? ✅the S phase on interphase
Interphase takes up what percent of the cell cycle? ✅the longest time
When does the centrosome replicate (duplicate)? ✅end of G1 and the beginning of S
phase
When is the centrosome duplication complete? ✅G2
When does the nuclear membrane fragment? ✅The end of prophase (reappears at
telophase)
What is a cohesive protein? ✅holds two sister chromatids together
What is a centrosome? ✅microtubule organizing center
When is the centrosome replicated? ✅interphase
What is a centromere? ✅waist structure of duplicated chromosomes where
kinetochores are formed
What do microtubules form? ✅mitotic spindles during mitosis and meiosis
How are spindles formed? ✅a-tubulin and b-tubulin proteins (through polymerization)
What is polymerization? ✅process in which large compounds are built by joining
smaller ones together
Microtubules grow from ______ and connect to _______ ✅centrosome; kinetochore of
duplicated chromosomes
, How do sister chromatids separate? ✅by depolymerization of microtubules from the
kinetochore side and degradation of cohesion proteins
Homologous chromosomes structure ✅Chromosomes that have the same sequence
of genes and the same length
Homologous Chromosomes ✅one of two paired chromosomes, one from each parent,
that carries genes for a specific trait at the same location
Alleles ✅different forms of a gene
What do duplicated homologous chromosomes form? When? ✅Tetrads during
prophase 1
Chromatid ✅replicated chromosome
Sister chromatids ✅two chromatids of a replicated chromosome
In what cells does mitosis occur? ✅Both somatic and reproductive cells
In what cells does meiosis occur?What do they form? ✅reproductive cells and
gametes
How does a zygote divide? Forms? ✅by mitosis and forms two daughter cells which
will divide further to form a multi cell embryo
How many chromosomes are there in a human somatic cell? ✅46 chromosomes (23
pairs)
How many chromosomes in a human egg or sperm? ✅23 chromosomes
What is the difference between cytokinesis of plants and animals? ✅plants have a cell
plate and animals form cleavage furrow
What is the name for bacterial cell division? ✅binary fission
In which cells do microtubules form within the nuclear membrane? ✅fungal yeast and
protist
What protein complex holds sister chromatids together? ✅cohesin complex
