Exam 4

When an organism is homozygous for one character, how many different kinds of gametes can it produce?

1 Gamete

When an organism is heterozygous for one character, how many differents kinds of gametes can it produce?

2 Gametes

Sexually reproducing organisms, such as humans, have 46 chromosomes in each cell. When human gametes are formed, how many chromosomes are in each mature gamete?

23

In the F2 generation what are the ratios of phenotypes and genotypes of a monohybrid cross?

3:1

When an organism is heterozygous for two different characters, how many different kind of gametes can it produce?

4 Gametes

In meiosis, how many cells result from original single cell?

4 genetically diverse cells from one original cell

What is the ratio of genotypes in a dihybrid cross?

9:3:3:1

How many chromosomes does a typical prokaryote possess?

A single DNA molecule

What chemical produced by aerobic respiration provides the energy that allows motor proteins, such as those in kinetochore, to "walk" along a microtubule?

ATP

What allows the cell to progress through the M checkpoint? Hint think metaphase.

All sister chromatids are correctly attached to the spindle microtubules

Where is the extrachromosomal DNA found in animal cells and in plant cells?

Any found outside the nucleus of a cell Eukaryote: organelles Prokaryotes: plasmids

Motor proteins on a nonkinetochore microtubule connect that to what other spindle structure?

Aster

Name the three kinds of mitotic spindle microtubules

Aster, Kinetochore, Nonkinetochore

Why do metaphase chromosomes look like the letter X?

Because they are two sister chromatid attach to each other in the centromere

What are the three key roles cell division plays in biology?

Cell reproduction, growth and development, and tissue renewal and repair

Where are the chromosomes found in eukaryotic cells?

Cell's nucleus

Where in the chromosome are the kinetochores attached?

Centromere

Distinguish centromere from centrosome and centriole.

Centromere: protein that holds sister chromatids together. How about the region of a chromosome where the microtubules of the spindle attach ?? Centrosome: a small organelle that separates chromosomes. Centriole: microtubules in centrosome that does the separating work

The points where non-sister chromatids are connected are ________.

Chiasmata

If an organism has 56 chromosomes in its somatic cells, how many sister chromatids are there after S (DNA synthesis) phase of the cell cycle?

Chromosomes doubles (56+56=112)

A group of individuals produced by asexual reproduction is called a ________.

Clone

What is the name of the protein that attach sister chromatids to each other?

Cohesin

Paring of non-sister chromatids in Prophase I is called _______.

Crossing Over

The signal to pass the G2 checkpoint and enter M phase is provided by two proteins called maturation promoting factor. One protein is present all the time and is called ____. The second protein is only present during late G2 and most of M phase and is called

Cyclin and Cdk

Chromosomes crossing over involves exchange of what macromolecule?

DNA

What are the two macromolecules that comprise chromatin?

DNA and Protein

What holds the tetrads together during late prophase I and metaphase I?

DNA. At a region called Xover

Where do paternal chromosomes come from?

Dad

What is the mechanism that lines chromosomes on the metaphase plate?

Dynamic Tension

What is Mendel's law independent assortment?

Each pair of alleles segregates independently of each other pair during gamete formation

When a hybrid cross is made, what is the name of the first generation of organisms?

F1 Generation

If cell density and the need to anchor to cell to a culture dish stop the cell cycle, what checkpoint is probably involved, G1, G2, or M?

G1

When a cell stops dividing , it withdraws from the cell cycle and enters the phase called G. What checkpoint probably stops the cell cycle for that cell?

G1

What is meant by G Phase?

Gap phase

An external signal that makes cells proceed through the cell cycle is provided by paracrine factors secreted by other cells and called _____.

Growth factors

Why is the G1 checkpoint considered the most important of the three, G1, G2 and M?

If a cells receives a go-ahead signal at the G1 checkpoint, it will usually complete the G1, S, G2, and M phases and divide.

In the F2 generations, which phenotypes are expressed?

In the F2 gen, 75% expressed the dominant trait and 25% expressed the recessive trait.

When we talk of the cell cycle we can divide it into two phases. The names of these two phases are?

Interphase and Mitotic (M) phase

The cell cycle really pertains to dividing cells. What is the definition of the cell cycle?

It is the life of a cell from the time it formed from a dividing parents until its own division into two cells

A picture containing all the chromosomes of an individual, organized by homologous pair is called a ________.

Karyotype

What is the name of the motor protein that attaches to each sister chromatid centromere?

Kinetochore

How many kinetochores are attached to each set of 4 chromosomes?

Kinetochore is attached to one chromosome of each tetrad

Growth of which microtubules probably separates the duplicated centrosomes.

Kinetochore microtubules

What is the location of a gene on a chromosome called?

Locus

What is the longest phase of meiosis and what process is taking place at that time?

Longest phase (takes up 90% of time) is Prophase I and the process is the exchange of DNA maybe?? Like cross-over happens and that takes awhile

How many maternal and how many paternal chromosomes are found in each human somatic cell?

Maternal: 23 (X) Paternal: 23 (X and Y)

What mitotic stage chromosomes are used in karyotype?

Metaphase

What are the two independent components of cell division called?

Mitosis and Cytokinesis

What are the two processes that occur during M phase?

Mitosis and Cytokinesis

What is meant by M phase?

Mitotic phase

Where do maternal chromosomes come from?

Mom

Human somatic cells have 46 chromosomes do algae, hedgehog, and elephant cells also have 46 chromosomes?

No, they vary in chromosomes 56 for elephants 90 for hedgehogs 148 for algae

What is a human somatic cell and how many sets of chromosomes does it possess?

Non reproductive cells and have two sets of chromosomes

If the kinetochore microtubules are breaking down as the chromosomes move along them, yet the spindle is still maintained, what microtubules maintain the spindle during anaphase and early telophase?

Nonkinetochore

Strictly speaking, what is mitosis?

Nuclear division

During metaphase II, how many kinetochores are attached to each sister chromatid?

One for each sister chromatid

During metaphase I, how many kinetochores are attached to each sister chromatid?

One kinetochore per duplicated chromosome

Which component of chromatin is responsible for DNA condensation?

Other bound proteins

What kind of organisms use cell division as a means of reproduction?

Prokaryotic cell and Unicellular Eukaryote

In which mitotic phase is the nuclear envelope still present?

Prophase

When we talk of the cell cycle we can divide it into 4 phases. The names of these four phases are?

Prophase, metaphase, anaphase, and telophase

What are the 5 phases of mitosis?

Prophase, prometaphase, metaphase, anaphase, and telophase

What happens to the chromosomes at each phase of mitosis?

Prophase: condense Prometaphase: attach to spindle MT's Metaphase: align at metaphase plate Anaphase: cohesins breakdown Telophase: reach opposite poles, decondense

What is the difference between the nucleus in prophase versus prometaphase?

Prophase: nuclear envelope Prometaphase: no nuclear envelope

What is a human gamete and how many sets of chromosomes does it possess?

Reproductive cells and have one set of chromosomes

Be familiar with the rule of addition and the rule of multiplication.

Rule of Addition: the probability that any one of two or more mutually exclusive events will occur is calculated by adding their individual probabilities Rule of multiplication: states that to determine this probability (two or more independent events will occur together in some specific combo), we multiply the probability of one event by the probability of the other event (see page 275)

At what phase of the cell cycle do the centromeres duplicate?

S phase

What is the name of the enzyme that cleaves the above protein at the end of metaphase?

Separase (Separin)

Chromosomes observed during mitosis are duplicated chromosomes. What is each member of the duplicated chromosome called?

Sister chromatids

Some organisms can reproduce without sex. We call that asexual reproduction. Give an example of asexual reproduction in a primitive animal, such as the hydra.

Starfish

What is meant by S phase?

Synthesis phase

In which mitotic phase is the nuclear envelope beginning to reform?

Telophase

How do you determine if an organism with the dominant phenotype is homozygous or recessive?

Testcross, which means a genetic cross between a homozygous recessive individual and a corresponding suspected heterozygote to determine the genotype of the latter

During metaphase I the chromosomes behave as groups of 4 chromatids called

Tetrads

As the chromosomes move to opposite poles of the cell during anaphase, the kinetochore microtubules appear to disappear,. At what end are the tubulin molecules dissociating - the end at the metaphase plate or the end at the centrosome?

The end at the metaphase

What is the expected outcome for a testcross involving a dominant phenotype with a recessive phenotype when the first organism is heterozygous?

The recessive trait will show in 2/4 offspring

Each of us has 22 pairs of somatic chromosomes. Each pair consists of two homologous chromosomes appears that same under the microscope and possesses the same sequence and the number of loci. What would we expect to find at each locus?

The same

How do nonkinetochore microtubules elongate the cell during anaphase and telophase?

They Lengthen

What is Mendel's law of segregation?

This law states that the two alleles for a heritable character segregate during gamete formation and end up in different gametes

When an organism is said to be homozygous for a particular trait, what does that mean about it's genotype?

This means its genotype contains JUST the dominant or recessive trait, not both. I.e. EE or ee but not Ee

When an organism is heterozygous, what does that say about it's genotype?

This means its genotype contains both the dominant and recessive trait (Ee)

Given a metaphase chromosome, identify the telomeres, arms, and centromere.

Top- Telomere Top- P-arm Middle- Centromere Bottom- q-arm Bottom- Telomere

Kinetochores can only move in one direction along the microtubule. During anaphase what is the direction a kinetochore will take toward the centrosome or away from the centrosome toward the midline?

Toward the centrosome

What are the proteins that are responsible for pinching off the two daughter cells during cytokinesis? Which one is a structural protein> Which one is a motor protein?

Tubulin: structural protein Myosin: motor protein

What makes kinetochores send a signal to the cell that delays anaphase?

When a kinetochores is not attached to spindle microtubules

During interphase is it possible to see individual chromosomes with the light microscope?

Yes

Can the environment produce different phenotypes even though the organisms have the same genotypes?

Yes, these results would be mutations

Explain why you know the genotype when you see a recessive phenotype expressed.

You know the genotype is ee because the recessive phenotype is expressed only if no dominant trait is present.

What is the definition of a genome?

a cell's genetic information

In a duplicated chromosome, how many kinetochores are attached to each sister chromatid? How many total for the duplicated chromosome?

a) 2 b)1

How does cytokinesis occur in plant cells? What is the cell plate? How are the two new cell membranes formed? Where do the cell wall materials come from?

a) During telophase, vesicles derived from the Golgi apparatus move along microtubules to the middle of the cell, where they coalesce. b) The beginning of a new cell wall. c) The cell plate enlarges until its surrounding membrane fuses with the plasma membrane along the perimeter of the cell. d) Golgi apparatus

For the character plant height, what are the alternative traits?

alleles

What is a kinetochore microtubule?

chromosome transport

What protein holds sister chromatids together in both mitosis and meiosis?

cohesin

What is a non-kinetochore microtubule?

extend spindle

Plant height, seed color, pod color, flower color are all examples of ______.

phenotypes

In the F1 generation, which phenotype is expressed-dominant or recessive?

purple. Dominant