Biology Exam Review

From Connect Assignment

The chromosome number in the body cells of most eukaryotic species falls within which range?

10 and 50

The cells of many eukaryotic organisms contain two sets of chromosomes and are said to contain a _____ number of chromosomes

diploid

What is the haploid number of chromosomes in humans?

23

In a diploid eukaryotic cell, a pair of chromosomes, one maternal and the other paternal, are known as _____ chromosomes. Each chromosome in a pair is termed a(n) ______

homologous; homolog

a karyotype is a visual representation of an individual’s _____

chromosomes

The haploid and diploid number of chromosomes in an organism are usually represented as ______

n for the haploid number, and 2n for the diploid number

Identify the diploid number of chromosomes in humans

46

In a homologous pair of chromosomes, what is the origin of each chromosome?

one is paternal and one is maternal

a visual representation of the number, size, and shape of chromosomes is called a _____

karyotype

one complete set of chromosomes necessary to define an organism is also known as the ____ number of chromosomes

haploid

chromatin is a complex with 40% DNA and 60% _____

protein

nucleosomes are composed of _____ and _____ proteins

DNA; histone

During cell division, chromatin becomes increasingly more condensed with one of the highest states of condensation seen in X-shaped metaphase chromosomes. In these structures, DNA is organized _______

on a protein scaffold

after DNA replication each condensed chromosome is made of two identical halves called _____ ______

sister chromatids

what is a sequence of growth, replication, and division that produces new eukaryotic cells called?

cell cycle

chromosomes are composed of chromatin which is a complex of DNA and ______

protein

what usually occurs in G1 phase?

cells are growing

histone proteins have a positive charge due to an abundance of ______ and _______

lysine; arginine

when DNA replicates, the sister chromatids are held together at their centromeres by what complex protein?

cohesins

in multicellular eukaryotic organisms, the production of new cells follows a highly regulated sequence of growth, DNA replication, and division. This sequence is referred to as the cell _____, which consists of the G1, S, G2, and M phases

cycle

in a cell’s life, cell growth occurs primarily during what phase?

G1

During the ___ phase of interphase in the cell cycle, the chromosomes are replicated

S

in the eukaryotic cell cycle, what is the name of the phase that occurs after the replication of DNA and before the start of mitosis.

G2

in actively dividing cells, the G1, S, and G2 phases are collectively known as what

interphase

the part of the cell cycle that is subdivided into five phases, during which the spindle apparatus assembles, binds to chromosomes, and moves sister chromosomes apart is ______

mitosis

in which phase of the cell cycle does the cytoplasm divide to produce two distinct daughter cells

cytokinesis

What is the first part of the M phase

mitosis

how long does a typical cell take to divide

24 hours

what phases in the cell cycle is considered a resting phase?

G0

in the body of an animal, some cells remain in the _____ phase permanently, while others can proceed to the G1 phase when new cells are needed (during an injury)

G0

in the cell cycle, the M phase consists of ____ (division of the nucleus) and ____ (the cell divides into two daughter cells)

mitosis; cytokinesis

while preparing to divide, the cells grows and copies its chromosomes during which stage?

interphase

mitosis occurs as a continuum of phases that proceed in the following order: ____, premetaphase, metaphase, _____, and lastly _____

prophase, anaphase, telophase

during the five phases of ______, the replicated genetic material is partitioned into ______ new nuclei

mitosis, 2

condensation of chromosomes is initiated in the _______ phase of interphase and continues until the end of prophase

G2

during the formation of spindle apparatus, what must break down?

nuclear membrane

during premetaphase, sister chromatids attach to the spindle by their ____, which are attached to the centromere region of each sister chromatid

kinetochores

during _____, the chromosomes are aligned midway between the spindle poles

metaphase

the metaphase plate is ______

perpendicular to the axis of the spindle and located halfway between the poles

what organelles reabsorbs the components of the nuclear membrane as it breaks down during prophase of mitosis?

endoplasmic reticulum

the pairs of sister chromatids align themselves in a single row along a plane half-way between the poles during which phase of mitosis?

metaphase

during metaphase, kinetochore microtubules move chromosomes to the middle of the cell where they are lined up on the _____ ______

metaphase plate

what is the shortest stage of mitosis

anaphase

during _____ of mitosis, the centromeres of sister chromatids split apart allowing sister chromatids to move away from each other

anaphase

what is a key event in anaphase?

removal of cohesion proteins from the centromeres of sister chromatids

when is the spindle apparatus broken down

telophase

during telophase, a _____ forms around each set of sister chromatids

nuclear envelope

during telophase, chromosomes uncoil to allow for gene

expression

the key event in anaphase is the simultaneous removal of ____ proteins from the centromeres of sister chromatids in all of cell’s chromosomes

cohesin

_______ is the final phase of mitosis

telophase

the ____ apparatus is broken down during telophase

spindle

what phase of mitosis is characterized by the reformation of the nuclear envelope and the production of two separate nuclei?

telophase

what enzymes control the progression of cells through the cell cycle checkpoints?

Cdks

if necessary, the cell cycle can be arrested at specific points called ____

checkpoints

cells control the cell cycle by integrating internal information and external signals and delaying the cell cycle at _____ checkpoints

3

protein kinases that regulate the cell cycle and are only active when complexed with the protein cyclin are called _____

cyclin-dependent kinases

the ____ enzymes control progression through the checkpoints in the cell cycle

Cdk

what checkpoint is the primary checkpoint at which external signals can influence the cell cycle?

G1/S checkpoint

During G2/M checkpoint of the cell cycle, the cell ____

assesses whether DNA has been successfully replicated

What are the three checkpoints in the cell cycle

→ Metaphase checkpoint

→ G2/M checkpoint

→ G1/S checkpoint

A _____ is a cluster of cancerous cells that have lost control of their growing

tumor

what type of genes were discovered in viruses and can cause a malignant transformation when introduced into a cell?

oncogenes

to cause cancer, both copies of a ______-_____ gene in a cell must lose function (usually through mutation)

tumor-suppressor

eukaryotes that reproduce through ____ reproduction require two cells to contribute genetic material for the production of the next generation

sexual

the spreading of cancer cells from the original tumor where they were produced to other areas of the body is called _____

metastasis

the two main classes of cancer-causing genes are ____ and tumor-suppressor genes

oncogenes

what type of cancer causing gene normally acts as a “brake” on the cell cycle, but loses this function when mutated?

a tumor-suppressor gene

typically, how many cells contribute genetic material during sexual reproduction

two

_____ is a term used to describe cells growing out of control

cancer

the two types of gametes typically produced by multicellular eukaryotic organisms are ______

→ sperm cells

→ egg cells

when two gametes unite, they produce a single cell called a(n) ______

zygote

____ is a reduction division which produces cells with half the normal number of chromosomes

meiosis

a cell is diploid when it carries ______

two sets of chromosomes

when two gametes fuse, they produce a single cell with twice the chromosomes of each gamete. This new cell is called a(n) _____

zygote

when reproduction is achieved through meiosis and subsequent fertilization, it is called ___ reproduction

sexual

a human gamete contains ________ chromosomes.

23

gametes are haploids, which means that they contain how many sets of chromosomes

one

how many rounds of cell division are required for meiosis?

2

synapsis (or pairing) of homologous chromosomes occurs during which process?

meiosis

what involves a physical change of DNA segments between homologous chromosomes

crossing over

what is the name for the sites of crossing over in a chromosome?

chiasmata

anaphase of mitosis separates ______ while anaphase 1 of meiosis separates ______

sister chromatids; homologs

during prophase 1, all four chromatids of two homologs become closely associated as a result of pairing, forming a structure known as a(n)

tetrad

when copies of genes that were formerly on seperate homologues can be found on the same homologue what has occured?

recombination has occurred

during which stage of meiosis do synapsis and crossing over occur?

prophase 1

a recombination ____ contains the enzymatic machinery necessary to break and rejoin the chromatids of homologous chromosomes

nodule

what is a unique behavior of kinetochores that allows the seperation of homologous chromosomes during meiosis 1

monopolar attachment

after crossing over is complete, the homologous chromosomes remain attached at the chiasmata. How many chromatids are attached at this point?

4

after metaphase 1, a pole may receive either the maternal or the paternal homologue from each chromosome pair, so chromosomes are said to assort ______

independently

the sister chromatids found in the daughter nuclei at the end of telophase 1 are not identical to each other due to what?

crossing over

some cells can undergo meiosis with ______ segregation, in which meiosis proceeds without recombination

achiasmate

at the end of anaphase 1 in meiosis, each pole of the cell contains what?

a haploid set of duplicated chromosomes

the sister chromatids are separated during which phase of meiosis 2?

anaphase

after meiosis is complete, what is produced?

four daughter cells that are haploid

when meiosis occurs without recombination, what has occured?

achiasmate segregation

when chromosomes do not segregate properly during meiosis, this is referred to as _____

nondisjunction

errors in meiosis can lead to gametes with the wrong number of chromosomes which are referred to as _____ gametes

aneuploid

when a cell undergoes meiosis, four daughter cells are produced. In terms of the number of chromosomes, each daughter cell contains a ____ nucleus

haploid