bio chapter 4 NSMO

Diameter of egg cell

100 micrometers

Diameter of blood cells

7-8 micrometers

As a cell continues to grow,

its volume increases while the surface area decreases

Making it harder to obtain nutrients and remove wastes

Surface area formula for a cube

SA = LxWx6

Volume formula for cube

V = s³

Cell division in bacteria

Binary fission

Cell cycle

1. Interphase

2. Mitosis (Equational Division)

3. Cytokinesis (Cytoplasmic Division)

Interphase

G₁ Phase (first growth phase)

Begins immediately after cell division

The cell grows, organelles double, and preforms its normal functions

—

S Phase (DNA Synthesis phase)

The cells genetic material (DNA) is getting replicated and duplicated

—

G₂ Phase (second growth phase)

Proteins are synthesized and the cell prepares for division

Mitosis

Occurs in somatic cells (2n) The duplicated genetic material separates, and the cell divides into two daughter cells, each having the same number of chromosomes (2n)

The purpose of mitosis is growth and replacement of damaged cells

Mitosis occurs in four stages

Prophase

The nuclear envelope disintegrates

The nucleolus disappears

Chromosomes condense and become visible

Spindle fibers form between the two poles of the cell

Metaphase

Chromosomes attach to the spindle fibers at the centromere

Chromosomes align along the equatorial plane of the cell

Anaphase

Spindle fibers contract and shorten

Sister chromatids are pulled toward opposite poles of the cell

Telophase

Chromosomes reach the opposite poles

A new nuclear envelope forms around each set of chromosomes

The nucleolus reappears

Chromosomes uncoil and return to a less condensed state

Spindle fibers disappear

Cytokinesis (Cytoplasmic Division)

In animal cells, the cell membrane constricts until the cell splits into two daughter cells, each containing the same number of chromosomes. In plant cells, a cell plate forms between the two newly formed nuclei, and then a cell wall develops, resulting in two genetically identical cells

CHEAT SHEET

Cytokinesis isn’t a stage of mitosis because mitosis is division of the nucleus and cytokinesis is the division of the cytoplasm, after all the stages of mitosis, cytokinesis finishes by separating the cell.

Cyclins (regulatory proteins) and kinase enzymes

both play a vital role in controlling normal progression of the cell cycle

Cells failing to respond

When cells fail to respond to the control mechanisms that regulate their life cycle, cancerous cells may result

Role of cyclins

Regulate the normal progression of the cell cycle

Activate the cell cycle in eukaryotic cells when they bind to cyclin - dependent kinases (CDKs), sending a signal to initiate cell division

Cancer

Uncontrolled and irregular growth and division of cells

Causes of cancer

Mutations or changes in segments of DNA that control the production of proteins responsible for regulating the cell cycle

Environmental factors and certain substances that cause cancer, known as carcinogens

Carcinogens

Asbestos, smoking, ultraviolet (UV) radiation, and X-rays

Apoptosis

Programmed cell death

It happens when cells shrink and condense in a controlled and organized manner

Apoptosis helps protect living organisms from the growth of cancerous cells

Stem cells

Undifferentiated cells capable of dividing and developing into specialized cells according to the type of tissue they join

Embryonic stem cells are more effective than adult stem cells

Stem cells contribute to treating many diseases, such as paralysis and organ dysfunction

Types of Stem cells

Embryonic stem cells

Adult stem cells

embryonic stem cells are more efficient than adult stem cells

Homologous chromosomes

Homologous chromosomes are pairs of chromosomes that have the same length, centromere position, and genes controlling the same inherited traits — one inherited from the father and the other from the mother. These pairs pair up during meiosis in a process called synapsis (crossing over)

Stages of meiosis

First stage - Meiosis I

Prophase I- Metaphase I- Anaphase I -Telophase I

In prophase I and metaphase I, the chromosomes appear as homologous pairs

In anaphase I and telophase I, the chromosomes appear as duplicated chromosomes

Cells in all phases of Meiosis I are diploid (2n) because the cell has not yet divided

Second stage Meiosis II

Prophase II – Metaphase II – Anaphase II – Telophase II

In prophase II and metaphase II, chromosomes appear as duplicated chromosomes

In anaphase II and telophase II, they appear as single chromosomes

In Meiosis II, the cells are haploid (1n)