AP bio unit 4- topic 4,5,6

What term describes the values for various physiological conditions that the body tries to maintain?

Homeostasis.

A physiological set point, like body temperature, has a _ for which it can fluctuate.

Normal range.

What is the physiological set point for human body temperature?

98.6°F.

What is the normal range for human body temperature?

97°F to 99°F.

What is homeostasis?

The state of relatively stable internal conditions.

In homeostasis, a change in the internal or external environment is known as a _.

Stimulus.

The body primarily maintains homeostasis through mechanisms known as _.

Feedback loops.

What are the two types of feedback loops?

Negative and positive.

In a feedback loop, what component detects a stimulus?

A receptor or sensor (e.g., sensory organs).

In a feedback loop, what component carries out the response?

An effector such as a muscle or gland.

How does a 'response' in a feedback loop relate to the 'stimulus'?

It changes the effect of the stimulus by increasing or decreasing it.

What is the most common feedback mechanism in the body?

Negative feedback.

How does negative feedback affect the stimulus?

It reduces the effect of the stimulus.

In the negative feedback example of body temperature regulation, what is the stimulus when you get too hot?

Heat.

In thermoregulation, what receptors detect an increase in body temperature?

Thermoreceptors in the skin.

What is the effector that responds to the stimulus of being too hot?

Sweat glands.

What is the response to the stimulus of being too hot?

Sweating.

In the negative feedback example of body temperature regulation, what is the stimulus when you get too cold?

Cold.

What is the effector that responds to the stimulus of being too cold?

Muscles.

What is the response to the stimulus of being too cold?

Shivering.

How does positive feedback affect a stimulus?

It increases the effect of the stimulus.

List two examples of positive feedback loops in organisms.

Childbirth, blood clotting, fruit ripening.

In the positive feedback loop of childbirth, what is the initial stimulus?

Baby pushing on the cervix.

During childbirth, what receptors detect the pressure on the cervix and send a signal to the brain?

Nerve cells in the cervix.

In the positive feedback loop of childbirth, what structure acts as the effector?

The pituitary gland (which releases oxytocin).

What is the response in the childbirth feedback loop that amplifies the original stimulus?

Oxytocin stimulates more contractions.

What is the term for a condition where the body is unable to maintain homeostasis?

Disease.

Diabetes is a disease characterized by the body's inability to regulate what?

Blood glucose levels.

To maintain homeostasis, cells in a multicellular organism must be able to _.

Communicate.

Cellular communication for homeostasis often occurs through what type of pathways?

Signal transduction pathways.

What are the three main purposes of the cell division process?

Reproduction, growth, tissue repair.

The _ is the life of a cell from its formation until it divides.

Cell cycle.

To form nucleosomes, DNA associates with and wraps around proteins known as _.

Histones.

Strings of nucleosomes form a substance called _.

Chromatin.

When a cell is not actively dividing, its DNA is in a non-condensed form called _.

Chromatin.

After DNA replication, chromatin condenses to form a densely packed structure called a _.

Chromosome.

The two identical, duplicated copies of a chromosome that are joined together are called _.

Sister chromatids.

What is the centromere?

The region where sister chromatids are most closely attached.

What is a kinetochore?

A protein structure on the centromere where spindle fibers attach.

What term describes all of a cell's genetic information (DNA)?

Genome.

What are homologous chromosomes?

Chromosomes (one from each parent) alike in size, shape, and gene content.

What type of cells are considered body cells and are diploid?

Somatic cells.

What does it mean for a cell to be diploid (2n)?

It has two sets of chromosomes.

What type of cells are reproductive cells (eggs/sperm) and are haploid?

Gametes.

What does it mean for a cell to be haploid (n)?

It has one set of chromosomes.

Human somatic cells are diploid and have a total of how many chromosomes?

46 chromosomes (2n=46).

The cell cycle consists of two alternating main phases: _ and mitosis.

Interphase.

What is the longest portion of the cell cycle, accounting for about 90% of the time?

Interphase.

What are the three sub-phases of Interphase?

G1, S, and G2.

During the _ phase of interphase, the cell is metabolically active, grows, and duplicates organelles.

G1 phase.

Cells that are not dividing and have exited the cell cycle are in a quiescent state known as the _.

G0 phase.

What is the key event that occurs during the S ('synthesis') phase of interphase?

DNA replication.

During the _ phase of interphase, the cell undergoes final growth and preparation for mitosis.

G2 phase.

What process involves the division of the nucleus?

Mitosis.

What process involves the division of the cytoplasm?

Cytokinesis.

Mitosis results in two genetically _ daughter cells.

Identical diploid.

What is the first stage of mitosis, where chromosomes condense and the mitotic spindle begins to form?

Prophase.

What happens to the nuclear envelope during late prophase (prometaphase)?

It breaks down.

What is the stage of mitosis where chromosomes line up at the cell's equator?

Metaphase.

During which phase of mitosis do paired sister chromatids separate and move to opposite poles?

Anaphase.

The separation of sister chromatids during anaphase is caused by the shortening of _.

Microtubules.

What is the final stage of mitosis, where two daughter nuclei form and chromosomes decondense?

Telophase.

In animal cells, cytokinesis occurs via the formation of a _.

Cleavage furrow.

In plant cells, cytokinesis occurs via the formation of a _.

Cell plate.

In a human somatic cell, how many chromosomes are present during prophase and metaphase?

46 chromosomes.

In a human somatic cell, how many chromatids are present during prophase and metaphase?

92 chromatids.

How many chromosomes are temporarily present in a human cell during anaphase, after the sister chromatids separate?

92 chromosomes.

After mitosis and cytokinesis are complete, how many chromosomes are in each human daughter cell?

46 chromosomes.

Control points that regulate the cell cycle are known as _.

Checkpoints.

Which checkpoint is considered the most important, determining if a cell will complete the whole cell cycle or enter G0?

G1 checkpoint.

What does the G2 checkpoint primarily check for before allowing the cell to proceed to mitosis?

Completion of DNA replication and DNA damage.

If irreparable damage is found at the G2 checkpoint, the cell will undergo _.

Apoptosis.

The M (spindle) checkpoint checks for what?

Proper attachment of spindle fibers to kinetochores.

The concentration of which internal regulatory proteins varies throughout the cell cycle?

Cyclins.

What is the function of enzymes known as cyclin-dependent kinases (CDKs)?

They trigger cell cycle events by phosphorylating other proteins.

CDKs are only active when their specific _ is present.

Cyclin.

What is the term for external signals, like hormones, that are released by cells to stimulate other cells to grow?

Growth factors.

What is contact (or density) inhibition?

Cells stop dividing when they touch other cells.

What is anchorage dependence?

Cells must be attached to a surface to divide.

Cancer is a disease caused by _ in genes that regulate cell growth.

DNA mutations.

How do cancer cells differ from normal cells regarding checkpoints?

Cancer cells ignore checkpoints and keep dividing.

Unlike normal cells that have a finite number of divisions, cancer cells can divide _ in culture.

Infinitely.

Cancer cells evade _, continuing to divide even when they have significant errors.

Apoptosis.

What is a benign tumor?

A mass of abnormal cells that does not spread.

A _ tumor is composed of cancerous cells that can spread to other parts of the body.

Malignant.

What is metastasis?

The spread of cancer cells from the original tumor to other parts of the body.