Biology; Cell Structure and Mitosis

Vocabulary and questions

Interphase

Cell grows and matures.

What makes up interphase? (GSG)

Stage G is cell growth, Cell S is when the DNA is duplicated, and G2 is the synthesis of organelles.

Prophase

First phase of mitosis. Condenses into chromosomes, each consisting of two chromatids conntect by a centromere. At the end of this phase, the nuclear membrane dissolves.

Metaphase

The centromeres of each chromesone attatch to fibers that change in length, pulling the chromosomes into a line along the center of the cell.

Anaphase

Centromeres split and chromatids are pulled to the opposite poles (sides) of the cell by the fibers. Phase is over when chromatids reach the poles and stop moving. During this process chromatids are now called daughter chromosomes.

Telophase

A nucleur membrane fomrs around each set of daughter chromosomes, and the nucleolus reappears in each nucleus. The daughter chromosomes now unwind into chromatin.

Cytokinesis

The dividing of two identical nuclei by spliting the cytoplasm and forming two daughter cells, each having a perfect copy of the parent cell's DNA

During which phase is the DNA duplicated? 

Interphase

What is the relationship between chromatin and chromosomes?

Chromatin is composed of DNA and proteins that condense to form chromosomes.

In which phase are chromatids pulled apart?

Anaphase

Spindle fibers

Cytoskeletal structure that seperate chromatids between daughter cells.

What is the role of the centrioles? 

To help form the spindle fibers.

In which phase does a new nuclear membrane develop?

Telophase

A cell has a single line of chromosomes. What is the phase?

Metaphase

During which phase are individual chromosomes visible?

Prophase

Why is it important that the cell’s DNA is duplicated before cell division? 

To ensure the cell gets all of it’s parent cell’s DNA.

Cells spend most time in which phase?

Interphase

What happens if cell division is not controlled?

Cancerous tumors can form.

What limits a cells size?

The Surface Area to Volume ratio and effiniency of DNA replication/cell division.

Apoptosis

A process of programmed cell death.

How is the cell cycle regulated?

The cell cycle is controlled by regulatory proteins both inside and outside the cell.

What are Cyclins?

A family of proteins that regulate the timing of the cell cycle in eukaryotic cells.

Lets cell cycle proceed only when certain steps have already happened

Internal Regulations

direct cells to speed up or slow down the cell cycle

External Regulations

respond to events outside the cell

External Regulations

respond to events inside the cell

Internal Regulations

Growth Factors

Wound healing and embryonic development

Cancer

Uncontrolled cell growth; cells do not respond to signals that regulate cell division or growth.

Process of Cancer Formation

1) A cell begins to divide abnormally.

2) Cells produce a tumor and start to displace normal cells and tissues.

3) Cancer cells move to other parts of the body.

Malignant tumor

Cancerous tumor.

Benign tumor

Noncancerous tumor. Does not spread to healthy tissue.

What is bad about cancer cells?

They absorb nutrients needed by other cells, block nerve connections, and prevent organs from functioning.

Metastasis

Invasion of healthy tissue by cancer cells.

What causes cancer?

Defects in genes that regulate cell growth and division.

Examples: smoking tobacco, radiation exposure, defective genes, and viral infection.

How do you treat cancer?

Many tumors can be treated with targeted radiation.

High-energy radiation is often used to treat cancer. Why is this treatment effective?

The radiation is especially damaging to cancer cells because of their high rate of mitosis.

Issues with cell size

The larger a cell = more demands on its DNA.

The rate of exchange depends on the surface area of a cell.

The rate of food and oxygen use and waste product production depends on the cell’s volume

Sexual Reproduction

Asexual Reproduction

Offspring that share an exact copy of their parent’s DNA are a result of…

Asexual Reproduction

Offspring that share a mix of each of their parent’s DNA are a result of…

Cons of Sexual Reproduction

Must find a mate, fewer offspring, offspring may be less well adapted to current conditions.

Cons of Asexual Reproduction

If conditions change, offspring not well adapted.

Pros of Sexual Reproduction

In changing environments, genetic diversity can be beneficial.

Pros of Asexual Reproduction

Don’t need to find a mate, offspring strive if in a stable environment, many offspring produced at a time.

How many chromosomes do humans have?

46

Cell cycle

Series of events that take place in a cell leading to its division and duplication. It consists of interphase (G1, S, and G2 phases) and mitosis (prophase, metaphase, anaphase, and telophase). During interphase, the cell grows, replicates its DNA, and prepares for division. Mitosis is the process of dividing the duplicated DNA and other cellular components equally into two daughter cells.