lesson 12 Chromosomes, Cell Cycle Regulation and Mitosis

Flashcards covering key vocabulary terms related to prokaryotic and eukaryotic genomes, chromosomes, the cell cycle stages (interphase and mitosis), cell cycle regulation, checkpoints, positive and negative regulators (cyclins, Cdks, Rb, p53, p21), cancer development, and prokaryotic cell division (binary fission).

What is a prokaryotic genome?

The entire genetic material of a prokaryote (like bacteria), usually a small, circular DNA molecule found in the cytoplasm, often with genes grouped in operons.

What is a eukaryotic genome?

The entire genetic material of a eukaryote (like humans), usually larger, linear DNA molecules neatly organized into multiple chromosomes inside the nucleus, wrapped around histone proteins.

What are chromosomes?

Structures inside cells that carry an organism's genetic information (DNA). Prokaryotes have one, while eukaryotes have many.

What are genes?

Specific sections of DNA that contain instructions for making RNA or proteins, passed down from parents to offspring.

What is Interphase?

The longest stage of a cell's life, where it grows, copies its DNA, and gets ready to divide. It includes G1, S, and G2 phases.

What happens during Prophase?

In mitosis, chromosomes become condensed and visible, the spindle begins to form, and the nucleus starts to break down.

What happens during Prometaphase?

In mitosis, the nucleus fully disappears, and the sister chromatids connect to the spindle fibers.

What happens during Metaphase?

In mitosis, sister chromatids line up in the middle of the cell, ready to be pulled apart.

What happens during Anaphase?

In mitosis, sister chromatids separate and move to opposite ends of the cell.

What happens during Telophase?

In mitosis, chromosomes uncoil, new nuclei form around them, resulting in two new nuclei.

What are homologous chromosomes?

A pair of chromosomes (one from each parent) that have the same genes in the same locations, but might have different versions (alleles) of those genes.

What are non-homologous chromosomes?

Chromosomes that do not pair up and carry different genes.

What are sister chromatids?

Two identical copies of a chromosome, joined together, formed when DNA is copied. They are separated during cell division.

What are non-sister chromatids?

Chromatids belonging to different chromosomes in a homologous pair.

What is the cell cycle?

The life cycle of a cell, a series of steps where it grows and divides into two new cells.

What is the Mitotic (M) phase?

The stage of the cell cycle where a eukaryotic cell divides into two identical daughter cells, including the division of the nucleus (mitosis) and the cytoplasm (cytokinesis).

What is Cytokinesis?

The final step of cell division, where the cell's cytoplasm and contents split into two separate daughter cells.

What is Karyokinesis?

Another name for mitosis, which is the division of the nucleus to equally distribute copied chromosomes into two new nuclei.

What is the G1 phase?

The first growth phase of a cell, where it grows larger, performs its normal jobs, and is very active biochemically.

What is the S phase?

The 'synthesis' phase where the cell copies all of its DNA, making two identical sister chromatids for each chromosome.

What is the G2 phase?

The second growth phase, where the cell gets ready for mitosis by storing energy, making more organelles, and rearranging its internal structure.

What does Haploid (1n) mean?

A cell that has only one set of chromosomes, like egg and sperm cells.

What does Diploid (2n) mean?

A cell that has two complete sets of chromosomes, one set from each parent, like most body cells.

What is a Nucleoid?

The central area in a prokaryotic cell (like bacteria) where its main DNA is found; it's not surrounded by a membrane.

What are Plasmids?

Small, extra rings of DNA found in prokaryotes, separate from the main chromosome, often carrying genes for useful traits like antibiotic resistance.

What is Chromatin?

The combination of DNA and proteins (histones) that makes up chromosomes inside the nucleus.

What are Histone proteins?

Proteins that DNA wraps around to condense itself into chromosomes within eukaryotic cells.

What are Nucleosomes?

The basic units of chromatin, formed when DNA wraps around a set of histone proteins, looking like 'beads on a string'.

What is Euchromatin?

Loosely packed chromatin that is actively being used to make RNA and proteins; these genes are often 'on'.

What is Heterochromatin?

Tightly packed chromatin where genes are usually 'off' and not being used.

What are Telomeres?

Protective caps at the very ends of chromosomes, made of special DNA and proteins, which prevent damage.

What are Centromeres?

The constricted (pinched-in) part of a chromosome where sister chromatids are held together, and where spindle fibers attach during cell division.

What are Cohesin proteins?

Proteins that act like glue, holding sister chromatids together from when they are copied until they separate in anaphase.

What is the Metaphase plate?

An imaginary line in the middle of the cell where chromosomes line up during metaphase of cell division.

What is the Cleavage furrow?

The pinching-in of an animal cell's membrane during cell division, which eventually splits the cell into two.

What is the Cell plate?

A new wall-like structure that forms in plant cells during division to separate the two new daughter cells.

What is the G1 Checkpoint?

A crucial 'stop/go' point in the cell cycle that checks if the cell is big enough, has enough resources, and if its DNA is okay before it copies its DNA.

What is the G2 Checkpoint?

A 'stop/go' point before mitosis that ensures the cell is ready, making sure it's big enough, has all its proteins, and that its DNA has been copied correctly and isn't damaged.

What is the Spindle (M) Checkpoint?

A 'stop/go' point during mitosis (metaphase) that confirms all chromosomes are correctly attached to the spindle fibers before they are pulled apart.

What are Positive Cell Cycle Regulators?

Proteins (like cyclins and Cdks) that act like 'accelerators' to push the cell forward through the cell cycle.

What are Negative Cell Cycle Regulators?

Proteins (like Rb, p53, p21) that act like 'brakes' to stop the cell cycle if something is wrong, preventing uncontrolled cell growth.

What is Cyclin?

A protein that helps control the cell cycle by binding to Cdk enzymes, and its levels go up and down predictably.

What is Cyclin-dependent protein kinase (Cdk)?

An enzyme that, when activated by cyclin, helps move the cell through different stages of the cell cycle by adding phosphate groups to other proteins.

What is Cyclin D?

A cyclin that helps the cell move from the G1 phase to the S phase.

What is Cyclin E?

A cyclin that helps transition from G1 to S phase and starts DNA replication.

What is Cyclin A?

A cyclin that helps start DNA replication and prepares the cell for mitosis.

What is Cyclin B?

A cyclin that helps the cell move from the G2 phase into the M (mitosis) phase.

What is a Proto-oncogene?

Normal genes that help cells grow. If they mutate, they can turn into oncogenes and cause cancer.

What is an Oncogene?

A mutated gene (from a proto-oncogene) that causes cells to grow uncontrollably, leading to cancer.

What is a Tumor suppressor gene?

Genes that normally work to stop cells from growing and dividing too much, helping to prevent cancer.

What is Rb (retinoblastoma protein)?

A tumor suppressor protein that controls the G1 checkpoint, making sure the cell is ready to divide.

What is p53?

A very important tumor suppressor protein, often called the 'guardian of the genome.' It stops the cell cycle at G1 or G2 to fix DNA damage, or triggers cell death (apoptosis) if the damage is too severe.

What is p21?

A protein activated by p53 that stops the cell cycle at the G1 phase by blocking other cell cycle proteins (Cdks).

What is Cancer?

A disease caused by uncontrolled cell division, often due to genetic mutations in genes that normally control cell growth.

What is Apoptosis?

Programmed cell death, a normal process that helps keep the number of cells in the body balanced.

What is Homeostasis?

The body's ability to maintain stable internal conditions, including keeping cell numbers balanced through cell division and cell death.

What is Binary fission?

The simple way prokaryotic cells (like bacteria) divide: they copy their DNA, grow longer, and then split into two identical daughter cells.

What is Ori?

The 'origin of replication' in bacteria, where DNA copying starts.

What is FtsZ?

A bacterial protein that forms a ring and helps prokaryotic cells divide by pinching them apart.

What is Tubulin?

A protein in eukaryotic cells that forms microtubules, which are important for cell structure and division. It's similar to FtsZ in bacteria.

What is Homology?

A similarity between different species (like FtsZ in bacteria and tubulin in eukaryotes) that suggests they share a common ancestor.