Biology Chapter 12 Flashcards

Questions and Answers

What must happen before a cell can begin mitosis? (Select all that apply)

The nuclear envelope must be duplicated.

The nucleus must divide in two.

The chromosomes must be duplicated. (correct)

A mitotic spindle must form.

The sister chromatids must be separated.

The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?

Prophase (correct)

Metaphase

Telophase

Interphase

Anaphase

The chromosomes line up in the center of the cell during which phase of mitosis?

Anaphase

Prophase

Interphase

Metaphase (correct)

Telophase

The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?

Anaphase Signup and view all the answers

The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?

Telophase Signup and view all the answers

At the end of the mitotic (M) phase, the cytoplasm divides in a process called _____.

cytokinesis Signup and view all the answers

If grasshopper cells contain 200 units of DNA during the G2 phase, how many units of DNA are present at G1 in one of the daughter cells?

100 units Signup and view all the answers

How many maternal chromosomes are present in a somatic human cell not engaged in cell division?

23 Signup and view all the answers

The quantity of DNA in the cells doubled _____.

between the G1 and G2 phases Signup and view all the answers

'Cytokinesis' refers to ______.

the division of the cytoplasm Signup and view all the answers

During what phase in the cell cycle would you find the most DNA per cell?

G2 Signup and view all the answers

The function of the mitotic cell cycle is to produce daughter cells that _____.

are genetically identical to the parent cell (assuming no mutation has occurred) Signup and view all the answers

During interphase, the genetic material of a typical eukaryotic cell is _____.

dispersed in the nucleus as long strands of chromatin Signup and view all the answers

Which of the following does NOT occur during mitosis?

replication of chromosomes Signup and view all the answers

DNA replication occurs in ______.

the S phase of interphase Signup and view all the answers

Tissue culture experiments with PDGF demonstrate that without this substance _____.

fibroblasts fail to divide Signup and view all the answers

In a human cell that is going through the cell cycle, when do the centrosomes separate?

prophase Signup and view all the answers

Down syndrome is characterized by cells having three copies of chromosome 21. As a cell in an individual with Down syndrome prepares to enter mitosis, how many chromatids would be present?

94 Signup and view all the answers

Which of the following hypotheses is best supported by observing cancer cells in a culture?

the cancer cells do not exhibit density-dependent inhibition Signup and view all the answers

If the human somatic cell is just about to divide, it has _____ chromatids.

92 Signup and view all the answers

Which of the events occur during anaphase?

all of the above Signup and view all the answers

Chromatids are _____

identical copies of each other if they are part of the same duplicated chromosome Signup and view all the answers

One event occurring during prophase is ______.

the beginning of the formation of a spindle apparatus Signup and view all the answers

A cell entering the cell cycle with 32 chromosomes will produce two daughter cells, each with _____

32 chromosomes Signup and view all the answers

The region of a chromosome in which the two double strands of replicated DNA are held together is called _____

a centromere Signup and view all the answers

The phase of mitosis during which the chromosomes move towards separate poles of the cell is _____.

anaphase Signup and view all the answers

The person credited with first recognizing (in the 1860s) that living cells cannot arise spontaneously, but arise only from previously existing cells, is _____.

Rudolf Virchow Signup and view all the answers

You would UNLIKELY be able to see which of the following human cells dividing?

nerve cell Signup and view all the answers

You would know that a dividing cell was a plant cell rather than an animal cell if you saw that ____.

it had formed a cell plate Signup and view all the answers

At which stage of mitosis are chromosomes lined up in one plane in prep for their separation to opposite poles of the cell?

metaphase Signup and view all the answers

Following cytokinesis in an animal cell, how many centrioles does each new daughter cell possess?

2 Signup and view all the answers

Which of the following is FALSE regarding sister chromatids?

Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred Signup and view all the answers

Which of the following processes does NOT occur in dividing bacteria?

mitosis Signup and view all the answers

During which stage of the cell cycle do sister chromatids separate?

anaphase Signup and view all the answers

Which of the following phases of mitosis is essentially the OPPOSITE of prometaphase in terms of the nuclear envelope?

telophase Signup and view all the answers

What is the difference between a benign tumor and a malignant tumor?

cells of benign tumors do not metastasize; those of malignant tumors do Signup and view all the answers

In telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in _____.

prophase Signup and view all the answers

Which of the following represents a mismatch or incorrect description?

metaphase: the nuclear envelope disappears Signup and view all the answers

The complex of DNA and protein that makes up a eukaryotic chromosome is properly called ____.

chromatin Signup and view all the answers

Which of the following is involved in the binary fission of most bacteria?

distribution of a copy of the single parental chromosome to each daughter cell Signup and view all the answers

The centromere is a region in which _____

sister chromatids are attached to one another in prophase. Signup and view all the answers

In animal cell mitosis, the cleavage furrow forms during which stage of the cell cycle?

cytokinesis Signup and view all the answers

If a cell contains 60 chromatids at the start of mitosis, how many chromosomes will be found in each daughter cell at the completion of the cell cycle?

30 Signup and view all the answers

Assume that you are dealing with a species in which the number of chromosomes in each somatic cell is 14. How many sister chromatids are present in the early telophase of mitosis?

0 Signup and view all the answers

When a cell in S phase is fused with a cell in G1, ______.

DNA synthesis begins immediately in the original G1 nucleus. Signup and view all the answers

During binary fission in a bacterium,_____

the origins of replication move apart. Signup and view all the answers

Study Notes

Mitosis Overview

Mitosis is a process where a cell divides to produce two identical daughter cells.
Key phases include Prophase, Metaphase, Anaphase, and Telophase.
Before mitosis begins, chromosomes must be duplicated during the S phase of interphase.

Phases of Mitosis

Prophase: Centrosomes separate, the nuclear envelope breaks down, and spindle fibers begin to form.
Metaphase: Chromosomes align at the cell's equator, preparing for separation.
Anaphase: Sister chromatids are pulled apart towards opposite poles of the cell.
Telophase: Chromatids reach the poles, the nuclear envelope reforms, and the chromatin uncoils.

Cytokinesis

Cytokinesis is the division of the cytoplasm, occurring at the end of the M phase.
In animal cells, a cleavage furrow forms during cytokinesis, while plant cells form a cell plate.

Chromosome and DNA Count

G1 phase contains half the amount of DNA as the G2 phase in daughter cells. Example: 200 units in G2 means 100 in G1.
Human somatic cells have 23 pairs of chromosomes (46 total), and 92 chromatids are present just before mitosis.
Following cytokinesis, each daughter cell possesses 2 centrioles.

Chromatid and Centromere

Sister chromatids are identical copies of a chromosome, joined at the centromere.
Chromatids are formed during the S phase of interphase and are separated during anaphase.

Cancer and Cell Division

Cancer cells do not exhibit density-dependent inhibition, leading to uncontrolled division.
PDGF (Platelet-Derived Growth Factor) is crucial for normal cell division; without it, cells like fibroblasts fail to divide.

Differences between Tumors

Benign tumors do not metastasize, while malignant tumors spread to other tissues.
Mitosis does not occur in bacteria; instead, they divide via binary fission.

DNA Replication

DNA replication occurs during the S phase of interphase.
Cells engaged in cell division do not replicate chromosomes during mitosis.

Other Concepts

Chromatin refers to the complex of DNA and proteins in eukaryotic chromosomes.
Chromosomes are at their most condensed state during mitosis, while interphase involves dispersed chromatin.
Virchow's hypothesis states that all cells arise from pre-existing cells, contradicting earlier notions of spontaneous generation.

Key Misconceptions

Alignment of chromosomes occurs in metaphase, not prophase.
Mitosis does not involve replication of chromosomes; this occurs in the S phase.

These notes encapsulate foundational concepts regarding mitosis, cell division, and related cellular mechanisms crucial for understanding biology at the cellular level.

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Test your knowledge on the key concepts of cell division with these flashcards focused on mitosis from Biology Chapter 12. Each question targets essential processes, such as chromatid separation and cell cycle phases, crucial for understanding cellular functions.