Chapter 3

Question 1

3 main parts of a cell

Answer 1

the plasma membrane (plasmalemma) , cytoplasm ( organelles (mini organs) and cytosol), and nucleus (genetic material contained here)

Question 2

plasma membrane

Answer 2

is a flexible yet sturdy barrier that surrounds and contains the cytoplasm of the cell
- communication amongst cells
- involved in diffusion

Question 3

cytoplasm

Answer 3

consists of all the cellular contents between the plasma membrane and the nucleus.
- this compartment has 2 components: cytosol (fluid portion of cytoplasm) and organelles = little organs

Question 4

nucleus

Answer 4

large organelle that houses most of a cell’s DNA– within the nucleus, chromosomes (single molecule of DNA) contain genes (hereditary units)

Question 5

Plasma membrane best described using something called the

Answer 5

fluid mosaic model – the molecular arrangement of the plasma membrane resembles a continually moving sea of fluid lipids that contains a mosaic of many different proteins.
Some proteins float freely, some are stuck. membrane lipids allow passage of lipid soluble molecules but act as a barrier for polar substances.
Some of the proteins in the plasma membrane allow movement of polar molecules and ions into and out of the cell. Other proteins can act as signal receptors or as molecules that link the plasma membrane to intracellular or extracellular proteins.
*look at diagram to memorize!

Question 6

lipid bilayer

Answer 6

two back to back layers made up of three types of lipid molecules- phospholipids, cholesterol, and glycolipids

Question 7

the bilayer arrangement occurs because the lipids are..

Answer 7

amphipathic= they have both polar and nonpolar parts.

Question 8

phospholipids, the polar part is the..

Answer 8

phosphate containing “head” which is hydrophilic (water loving). the non polar parts are the two long fatty acid “tails” which are hydrophobic (fearing water).

Question 9

lipid

Answer 9

fat – has both polar and nonpolar
fats don’t like water – outer is okay with water but inner part is not okay with water
it is malleable (there’s movement)
image- bowl filled with ping pong balls– you can put your hand in and move it around, but as soon as I go to a new spot, the old spot is filled.

Question 10

passive transport

Answer 10

no energy needed
Passive processes:
S: simple diffusion - unassisted across membrane
F: facilitate diffusion -
O: osmosis – typically water specific

Question 11

active transport

Answer 11

energy needed
Active processes
P : primary and secondary transport
V : vesicular transport

Question 12

Plasma membranes are…

Answer 12

selectively permeable.
The lipid bilayer is always permeable to: small, nonpolar uncharged molecules

Transmembrane proteins that act as channels or transporters: increase the permeability of the membrane

Macromolecules are only able to pass through the plasma membrane by: vesicular transport

Question 13

Gradients Across the Plasma Membrane

Answer 13

concentration gradient is the difference in the concentration of a chemical between one side of the plasma membrane and the other
An electrical gradient is the difference in concentration of ions between one side of the plasma membrane and the other
Together, these gradients make up an electrochemical gradient

Question 14

Diffusion is influenced by:

Answer 14

S- steepness of the concentration gradient
T- temperature
M - mass of diffusing substance
S - surface area
D - diffusion distance

Question 15

Active transport : primary

Answer 15

Energy derived from ATP changes the shape of a transporter protein which pumps a substance across a plasma membrane against its concentration gradient

Question 16

Cytoplasm and 2 components

Answer 16

cytosol - also known as the intracellular fluid portion of the cytoplasm
organelles - the specialized structures that have specific shapes and perform specific functions

Question 17

Cytoskeleton

Answer 17

diagram – handouts on canvas – table
goal is to help with structure– maintain our shape and a little bit of movement
firm strings throughout cell

Question 18

centrosome/centrioles

Answer 18

dense areas of cytoplasm (liquid)
centrioles help form our cytoskeleton

Question 19

Cilia and Flagella

Answer 19

won’t find these on all cells
cilia – small hair like projections – in small intestine
both are focused on movement
flagella – sperm - projection at the end of it that causes movement
much more cilia on something- flagella would be just a few

Question 20

Ribosomes

Answer 20

very important in protein synthesis (making proteins)
proteins are most diverse (from lipids and carbs, etc)

Question 21

Endoplasmic reticulum (ER)

Answer 21

rough er has ribosomes, smooth does not

Question 21

Golgi complex

Answer 21

long, folded over itself
cells sorted through

Question 22

Lysosomes

Answer 22

destructors– they can break down worn out organelles
can kill stuff

Question 23

Nucleus

Answer 23

The nucleus contains the hereditary units of the cell, called genes
Genes are arranged along chromosomes
site of protein transcription
DNA - stays in nucleus - and Rna - mrna gets to leave

Question 24

Protein synthesis

Answer 24

the proteins determine the physical and chemical characteristics of the cell
the instructions for protein synthesis is found in the DNA nucleus
protein synthesis involves transcription and translation

shape determines function - common in proteins
when we are making a protein it is going to be determined by our genetic material
our dna is going to write a code, send it to the mrna, which will take it out and translate that code and that code says what the amino acid sequence will be
tmrna to translates the message

Question 25

Gene expression

Answer 25

synthesis of a specific protein requires transcription of a gene’s DNA into RNA and translation of RNA into a corresponding sequence of amino acids
our DNA is a double helix – when it passes the info to the mrna it will be se a single helix – that has the coding sequence so it can be paired up and decoded

Question 26

Transcription

Answer 26

Transcription occurs in the nucleus and is the process by which: genetic information encoded in DNA is copied onto a strand of RNA to direct protein synthesis

Question 27

Transcription in steps

Answer 27

Transcription is catalyzed by RNA polymerase.
Steps:
1. Messenger RNA (mRNA) directs protein synthesis
initial code
2.Ribosomal RNA (rRNA) joins with ribosomal proteins to make ribosomes
join at the site of the ribosome to make ribosomes
3.Transfer RNA (tRNA) binds to amino acid and holds it in place during translation
brings amino acids over and connect with the rRNA to make the string of amino acids
by reading the code from mRNA they know where it goes

Question 28

Translation

Answer 28

Translation occurs outside the nucleus and is the process of: reading the mRNA nucleotide sequence to determine the amino acid sequence of the newly formed protein
outside the nucleus

Question 29

Interphase – will take up most of the time of cell division -

Answer 29

G1 phase
-checkpoint– once you get past this point duplication will occur
if there is an error it will self destruct
-growth
S
-duplicating
G2 phase
-growth

Question 30

when does mitosis occur

Answer 30

when the nucleus of a cell divides

Question 31

Mitosis results in the distribution of:

Answer 31

2 sets of chromosomes into 2 separate nuclei

Question 32

4 stages of mitosis

Answer 32

Prophase
Metaphase
Anaphase
Telophase

Question 33

Mitosis: Prophase : “before”

Answer 33

During prophase chromatin condenses into chromosomes and the nuclear membrane disappears and centrosomes move to opposite poles
-chromosomes are condensing (thickening)

Question 34

Mitosis: Metaphase : “middle”

Answer 34

During metaphase centromeres of chromosomes line up in middle in a single file line – at the metaphase plate

Question 35

Mitosis: Anaphase : “away”

Answer 35

During anaphase centromeres of chromosomes split and sister chromatids move toward opposite poles of the cell
-chromatids are pulled away to opposite sides by the spindles

Question 36

Mitosis: Telophase

Answer 36

During telophase the mitotic spindle dissolves, chromosomes regain their chromatin appearance, and a new nuclear membrane forms
-new nuclei form
-cytokinesis occurs to form 2 diploid cells (46 chromosomes)
identical

Question 37

Cytokensis

Answer 37

During cytokinesis a cleavage furrow forms and eventually the cytoplasm of the parent cell fully splits
When this is complete, interphase begins

Question 38

Control of Cell Destiny
Three possible destinies:

Answer 38

Remain alive and function without dividing
Grow and divide
Die

Question 39

(Meiosis I) prophase I:

Answer 39

chromosomes condense to match with a similar partner (1 from dad and 1 from mom) they cross over and exchange material
difference from mitosis: but they are also looking for a partner, they swap genetic material with each other

Question 40

metaphase 1:

Answer 40

chromosomes line up in the middle in pairs
difference: they’re in pairs not single like mitosis

Question 41

anaphase 1:

Answer 41

chromosomes pulled to opposite sides of cell
difference: chromosomes not chromatids

Question 42

Telophase 1

Answer 42

new nuclei form
cytokinesis takes place
end up with 2 cells – non identical
still at 46 chromosomes

Question 43

Meiosis 2

Answer 43

prophase II: chromosomes condense - 2 instead of one
metaphase II: chromosomes line up in the middle– single file line
anaphase II: chromosomes are pulled to opposite sides of the cell
telophase: new nuclei form
Cytokinesis takes place to split into 4 haploid cells that are non-identical and contain 23 chromosomes
-mitosis is more similar to mitosis 2 than one

Question 44

Aging and Cells

Answer 44

Our cells gradually deteriorate in their ability to function normally and in their ability to respond to environmental stresses
The numbers of our body cells: decreases
We lose the integrity of the extracellular components of our: tissues