Radiation Biology: Ch. 6 pages 98-109

what parts make up a cell

• cell membrane

• cytoplasm

• cytoplasmic organelles

• nucleus

frail, semipermeable, flexible structure that encases and surrounds the cell

cell membrane

what is a cell membrane made up of

lipids and proteins

what is the function of a cell membrane

barrier to protect contents from the outside environment and controls passage of water and materials into and out of cell

-primary role in cells transport system

protoplasm that exists outside the cells nucleus

cytoplasm

what is the cytoplasm consisted of

primarily water, proteins, carbohydrates, lipids, salts, and minerals

-makes up majority of the cell

where do cellular metabolic functions occur

cytoplasm

4 major functions of the cytoplasm

1. accepts unrefined and assembles them into new substances, i.e proteins

2. breaks down organic materials to produce energy

3. packaging substances for distribution to other areas of the cell or various sites in body

4. eliminating waste products

“tiny organs”, tiny tubules, vesicles, granules, and fibrils that perform various functions of the cell

cytoplasmic organelles

what determines the function of each organelle, what carries those instructions into the cytoplasm

DNA determines the function and mRNA carries the instructions into the cytoplasm

what are the 6 major organelles

1. endoplasmic reticulum

2. golgi complex

3. mitochondria

4. lysosomes

5. ribosomes

6. centrosomes

highway system of the cell, food transfer, passageway for mRNA

endoplasmic reticulum (ER)

what is the ER makeup

tubules that spread in all directions throughout the cytoplasm, which enables the cell to communicate with extracellular environment

two types of endoplasmic reticulum

1. rough surfaced (ribosomes)

2. smooth surface (no ribosomes)

hauls “freight” within the and out of the cell, located near the nucleolus and extends to the cell membrane

golgi apparatus/complex

what does the golgi apparatus/complex do

• unites large carbohydrate molecules and combines them with proteins to form glycoproteins

• ifa cell manufactures enzymes or hormones , it concentrates and transports them through the cell membrane into blood stream

large bean like structure known as the “power generating station” of the cell

mitochondria

what do mitochondria do

• produce energy for cellular activity by breaking down nutrients through oxidations

• some enzymes in mitochondria are essential in the production of adenosine triphosphate (ATP)

prime energy containing molecule in the cell

ATP

essential for sustaining life and plays an important role in active transport within the cell, varies from cell to cell but the greatest number is found in cells with greatest activity

mitochondrial ATP

small pea like sacs containing digestive enzymes, “garbage bags with poison pills”

lysosomes

function of lysosomes

digestive organs of the cell, help control intracellular contaminants, and dispose of bacteria and food

what happens if lysosomes fail to dispose

accumulation of “stuff” which may be toxic

why are lysosomes termed “suicide bags”

the enzymes contained can break down and digest the cell itself when lysosomes membrane breaks

rupture can happen when exposed to radiation, cell will likely die

small spherical organelles that attach to endoplasmic reticulum, “manufacturing facilities of the cell”

ribosomes

of what do ribosomes consist of

2/3 RNA 1/3 protein

function of ribosomes

• “protein factories”, job to manufacture the various proteins that the cell requires

• site of protein synthesis

“weavers of the spindle” located in the center of the cell near nucleus

centrosomes

what do centrosomes contain

centrioles, pairs of small hallow cylindrical structures that are believed to play a role in the formation of the mitotic spindle during cell division

“information processing and administrative center”

nucleus

how is the nucleus seperated from other parts of the cell, and what does it contain

nucleus is separated by a double walled membrane with pores called the nuclear envelope, the nucleus contains DNA and the rounded body called the nucleolus which is the RNA copy center

what is cell divison

multiplication process whereby one cell divides into 2 or more cells (cell proliferation)

two types of cell division

1. mitosis for somatic cells

2. meiosis for germ cells

germ cells-females have ____ and males have ______

ovum, spermatozoa

what are the two reasons for mitosis in somatic cell division

• repair of damage

• growth of new tissue

what is mitosis, what does it form?

2 daughter cells identical to the parent, approx. equal distribution of all cellular material between 2 daughter cells

-46 chromosomes each

4 distinct phases of a cell life cycle

M-mitosis

G1- gap in cell growth/ pre DNA synthesis

S-synthesis

G2-post DNA synthesis

which stage is least radioresistant (most radiosensitive)

mitosis

which stage is the most radioresistant (least radiosensitive)

synthesis

2 categories of cell life cycle

M-phase and interphase

what does the M-phase consist of

4 different phases: prophase, metaphase, anaphase, telephase

what does interphase consist of

G1 through G2, period of cell growth between divisions

when the nucleus swells, DNA begins to take form is _____

prophase

when chromosomes appear lined up in middle of nucleus is ______

metaphase

when chromosomes are split apart is ______

anaphase

when the split chromosomes disappear into its own DNA mass, nuclear membrane closes off is ______

telophase

during which phase can radiation damage be seen with a microscope

metaphase

cell-time:

also known as generation time, is the average time from one mitosis to another

what is the average cell-time or generation time for most cells

10-20 hours

some specialized cells have a cell-time or generation time of how many hours

several hundred

division of primary genetic cells

meiosis

what does meiosis do

reduces the number of chromosomes in each daughter cell to ½ the number of chromosomes in the parent cell

2 steps of meiosis and what do they do

1. replication-division: cell proceeds through the same phase of mitosis like somatic cells

2. reduction-division: the daughter cells from first step, undergo another division but without the S-phase

which step of meiosis are no chromosomes are duplicated

reduction

what is the end result of meiosis

4 cells with 23 chromosomes each, so when combined with another germ cell the result is a cell with 46 chromosomes