Genetics chapter 2 Chromosomes and cellular reproduction

Prokaryotic cells reproduce via what?

Binary fission

What is binary fission

The simple process where the single, circular DNA molecule replicates, and the cell divides into two identical daughter cells.

Eukaryotic DNA is complexed with histone proteins and is enclosed within what?

A nuclear envelope

Sexual reproduction, as described in the context of eukaryotes, involves the fusion of gametes produced via what?

Meiosis

What domains do prokaryotes belong to

Eubacteria and Archaea

Cell structure of prokaryotes?

Lack membrane-bound organelles and a nucleus.

What cell structures do prokaryotes typically have

Cell wall, plasma membrane, ribosomes, and a single circular DNA molecule

What does the DNA of prokaryotes look like?

The DNA is not highly organized and is not complexed with histones.

Where does the DNA of prokaryotes reside?

The nucleoid

Cell structure of eukaryotes?

They are larger than prokaryotic cells and possess membrane-bound organelles, including a nucleus

What does the DNA of eukaryotes look like?

It is organized into multiple linear chromosomes.

In Eukaryotes, each chromosome consists of DNA tightly associated with what?

Histone proteins, which forms chromatin

The DNA of eukaryotes is enclosed within what?

Nuclear envelope

Haploid (n)

Contains one set of genetic information

Diploid (2n)

Contains two sets of genetic information, one set inherited from each parent

Homologous pairs

occurs in diploid organisms where 2 chromosomes correspond to each other. One inherited from each parent that carry the same genes but may have different alleles

What is the centromere of a chromosome?

A constricted region where kinetochores form, serving as attachment points for spindle microtubules

What are the telomeres of chromosomes

The stable tips of linear chromosomes

Origins of replication

Sites where DNA synthesis begins

Chromatids

Before replication, a chromosome has one chromatid. After replication, it consists of two identical sister chromatids joined at the centromere

What type of chromosome is this?

Submetacentric

What type of chromosome is this?

Metacentric

What type of chromosome is this?

Telocentric

What type of chromosome is this?

Acrocentric

Phases of the Cell Cycle

Interphase → M phase → Phase checkpoints in between

Phases of interphase

G₁ → S → G₂

G₁ of interphase

Growth occurs and proteins necessary for cell division are synthesized

G₀ of interphase

occurs when cells exit the active cell cycle to enter a resting, non-dividing state. Cells enter this phase to conserve energy, complete specialized jobs, or respond to a lack of nutrients and signals

G₁ / S checkpoint

key control point at the end of the G1 phase where a cell decides if it is ready to divide. It stops the cell cycle before DNA replication begins to prevent damaged cells from multiplying

S phase of interphase

a critical period in interphase where a cell replicates its entire genome. Occurring between the G1 and G2 phases, it ensures that each future daughter cell receives an identical, complete set of genetic material

G₂ phase of interphase

The final subphase of interphase. Occurs after S phase and precedes mitosis. Cell continues to increase in size here and produces extra proteins, RNA, and duplicates remaining organelles needed for cell division.

G₂ / M checkpoint

cellular quality control station located at the end of the G2 phase, right before mitosis (M phase). Its main job is to make sure DNA replication is complete and that any damaged DNA is fixed before the cell divides.

M phase

Consists of Mitosis and Cytokinesis and takes place after interphase

Mitosis

Separation of sister chromatids

Cytokinesis

Separation of cytoplasm; the cytoplasm divides and the cell wall forms in plant cells

What is the order of mitosis

Prophase → Prometaphase → Metaphase → Anaphase → Telophase

Prophase of mitosis

Chromosomes condense and the mitotic spindle forms

Prometaphase of mitosis

Nuclear envelope disintegrates and spindle microtubules anchor to kinetochores

Metaphase of mitosis

Chromosomes align on the metaphase plate; spindle-assembly checkpoint

Anaphase of mitosis

Sister chromatids separate, becoming individual chromosomes that migrate toward spindle poles

Telophase of mitosis

Chromosomes arrive at spindle poles, the nuclear envelope re-forms and the condensed chromosomes relax

Spindle microtubules are composed of what?

Tubulin Subunits

The positive end of spindle microtubules attach where

To the kinetochore at the centromere

The negative end of microtubules attach where?

At the spindle pole in the centrosome

Tension along the microtubules allows for indication where?

At the checkpoints

Microtubules disassemble at both ends to do what?

To pull chromatids apart