Finals Prep Biology: Unit 5 - Cell Growth And Division

Explain why cells cannot grow too large

Large cells have low surface area to volume ratio, so they don't have enough surface area to exchange materials and with that, have a hard time moving materials through the cell

They also develop information crises which occurs because larger cells need more resources and the DNA in the nucleus is unable to direct all that needs to occur in the cell

Describe the structure of a replicated chromosome

Two sister chromatids joined at the centromere

List the stages of the cell cycle and describe what happens in each

G1/Gap 1 - growth, normal metabolic functions

S/Synthesis - copying all DNA

G2/Gap 2 - organizing the cell for division

M/Mitosis - nuclear division

C/Cytokinesis - division of cytoplasm

Function of mitosis (growth and repair)

Organisms grow by accumulating more and more cells, so mitosis helps by contributed to the repair of damaged tissues by replacing dead or damaged cells

it can also increase or decrease depending on if there are gaps between cells (skin cuts)

Explain how cancer occurs

When cells are resistant to the prevention tactics of cell cycle checkpoints, they can continue dividing rapidly, forming a tumor

When cells break off from a malignant tumor, they can travel through vessels and begin growing in other tissues, causing a more serious cancer

Explain how cancer is treated

Surgery - removing the tumor

Chemotherapy - drugs designed to interfere with cell division are administered orally or with IV and attack all cells that rapidly divide and produce a lot of protein

Radiation - X-rays are directed at the tumor cells and is meant to damage the DNA of the tumor cells in order to kill them off

Explain the role of stem cells in the body

They are unspecialized, allowing them to contribute to the development of different types of tissues and organs

Distinguish between the three types of stem cells

Totipotent - can become any cell type in the baby or placenta and membranes

Pluripotent (embryonic) - can become any cell type in the baby

Multipotent (adult) - can become a limited number of different, but related, cells in the body

Describe how cells differentiate

By turning different genes on and off at different times

List the levels of organization in living things form simplest to most complex

Cell

Tissue

Organ

Organ System

Organism

Cell Division

Produces two daughter cells

Purpose is to make more, smaller cells in order to keep the surface area to volume ratio high so it can properly carry out all of its necessary functions

Asexual Reproduction

A single parent produces genetically identical offspring

Occurs in almost all unicellular organisms and some multicellular organisms, but only by cell division

Sexual Reproduction

Involves the fusion of two separate parent cells to create genetically unique offspring with some traits from each parent

Binary Fission

A simple type of asexual reproduction in which a cell duplicates its DNA and divides into two daughter cells that are identical to another

Cell Cycle

The process of a cell growing, preparing for division, and dividing to form two daughter cells

Interphase

Separates the cell divisions from one another

Consists of three stages - G1, S, and G2

G0

Permanent interphase for cells that aren't going to divide, so cells aren't actively dividing or preparing to divide

G1

The cell grows before it can divide again, performs its function, and prepares to copy its DNA

Cell Growth

S

Copies all DNA

DNA replication

G2

Cell performs its function and prepares for cell division

Preparing for cell division

Mitosis

The cell division process in which one cell divides into two identical daughter cells

Consists of 4 stages PMAT

Cytokinesis

The division of the cytoplasm to form two separate cells and completes the process of cell division

Prophase

The first stage of mitosis, taking up nearly half of the time

P for poles - early in prophase, the centrioles (only animal cells) and/or chromosomes (only plants) move towards opposite ends/poles of the cell

Nuclear membrane 'disappears'

Chromosomes condense

Centromeres begin to seperate

Spindle begins to form

Metaphase

The second, and generally shortest phase of mitosis

M for middle - the centromeres of duplicated chromosomes line up in the middle of the cell

The spindle fibers also connect the centromeres of each chromosome to the poles

Anaphase

A for away - sister chromosomes separate and begin to move apart so that each sister chromatid is now an individual chromosome

Completes when the movement stops and the chromosomes are completely split into two groups

Results in the microtubules being almost completely dissasembled

Centromeres split

Spindle fibers attached to chromosomes shorten

Sister chromatids pulled toward opposite ends of the cell

Remaining spindle fibers lengthen to stretch the cell

Scaffolding for cell wall begins to form (plants)

Ring of protein fibers forms at the midline of the cell (animals)

Telophase

Final phase of mitosis

T for two - chromosomes become spread out into a tangle of chromatin, and the nuclear envelope forms around each cluster until a nucleus becomes visible

Chromosomes begin to decondense

Nuclear membrane surrounds chromosomes

Spindle breaks down

Cell plate begins to form (plants)

Ring of protein fibers around center of cell begins to pull inward (animals)

Chromosome

Genetic information bundled into packages of DNA

Chromatin

Located in the nucleus consisting of DNA and its associated proteins

Histone Protein

Help to condense DNA into chromatin and later form chromosomes

Also contribute to the regulation of gene expression and DNA replication

Sister Chromatids

Identical copies of a single chromosome, formed after a chromosome replicates during cell division

Centromere

The middle of a chromosome, where the two identical copies of DNA are held together and where the spindle attaches during cell division

Centriole

An organelle that plays a crucial role in cell division and the organization of mictrotubules

Spindle

A structure composed of microtubules that is essential for cell division, forming in prophase and metaphase and being used and disassembled in anaphase

Growth Factor

naturally occurring proteins that regulate cell growth and act as signaling molecules (used during wound healing, embryonic development, etc)

Cyclin

Proteins that regulate the cell cycle

CDK

Cyclin-dependent kinase (partners of cyclins) that add a phosphate group to other molecules

Adoptosis

A process of programmed cell death that holds an important role in structuring tissues during growth and development

Through a series of controlled steps for self destruction, the unneeded cells are killed off

Cancer

Occurs when a cell divides uncontrollably and forms a tumor, displacing normal cells and tissues until it begins to spread around the body

The cancer cells don't respond to normal regulatory signals so they disrupt the cell cycle and other cells and tissues in the body

Tumor

A growth formed by uncontrollable cell division that displaces normal cells and tissues

Benign

A non cancerous tumor/growth

Malignant

A cancerous tumor/growth

Stem Cell

Unspecialized cells from which differentiated cells develop, found in the early embryo and other places in the adult body

Totipotent

Able to do everything and develop into any type of cell in the body (only fertilized egg and cells produced by the first few cell divisions)

Pluripotent

Cells that can develop into any of the body's cell types other than the tissue surrounding the embryo

Multipotent

The ability to differentiate into multiple, but limited, specialized cell types

Tissue

A group of similar cells that work together to perform a specific function within an organism

Organ

A self-contained structure composed of different tissues that work together to perform a specific function within a living organism

Organ System

A collection of organs that work together to perform a specific, complex function in the body