PCB 3703C Ahangari Exam 1 UCF

Cell

Cells are the basic structural

and functional units of life.

How many cells are in the human body?

50-100 trillion

What are the three main regions of the cell?

plasma membrane

cytoplasm

nucleus

What are other names of the plasma membrane?

Plasmolemma

Fluid Mosaic Model

What is the base structure of the plasma membrane?

Lipid bilayer with embedded proteins

What are some of the lipids that make up the plasmolemma?

phospholipids, cholesterol + glycolipids

Most abundant lipid in plasmolemma?

Phospholipids

Phospholipid heads are

hydrophilic, polar

Phospholipid tails are

hydrophobic, lipidphillic + nonpolar

Most abundant proteins in membrane?

Integral

Some integral proteins can act as

receptors

Which side are peripheral proteins mostly on?

cytoplasmic

What is something peripheral proteins do?

support the cytoplasmic side of

the membrane by a network of filaments

What is the glycocalyx?

An extracellular sugar coating that provides protection to the cell

What is the function of the glycocalyx?

cell-to-cell binding and

recognition

Where is the glycocalyx located?

extends from glycolipids and glycoproteins to the outside of the cell

Some functions of the plasmolemma

-An external barrier against outside forces

-external proteins act as receptors in cell-cell recognition

-transport of substances in and out of the cell

What is allowed to enter the cell?

selectively permeable plasmolemma only allows small nonpolar, and some small polar things into cell

Larger molecules are blocked, and some may be able to go through protein transport

Passive diffusion is

down the concentration gradient

no ATP needed

What is transported through passive diffusion?

small, uncharged molecules like oxygen, Co2 and fat soluble molecules across the membrane

What is active transport?

low to high concentration movement

ATP needed

What is transported through active transport?

most larger water-soluble or charged

molecules, such as glucose, amino acids and ions are transported

by a pump or carrier and involve the integral proteins

How large particles and macromolecules pass through the plasmolemma?

Vesicular/bulk transport

What is exocytosis?

a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.

What is endocytosis?

the taking in of matter by a living cell by invagination of its membrane to form a vacuole.

What proteins help with exocytosis?

vSNAREs and tSNAREs

How do vSNAREs and tSNAREs work?

Proteins extending from the vesicle

membrane vSNAREs, bind with plasma

membrane proteins, the tSNAREs (t for

target), this causes the lipid layers of

the vesicle and cell membrane to join

together.

What protein is causes deformation of plasma membrane during endocytosis?

Clathrin protein

The three types of endocytosis

phagocytosis

pinocytosis

receptor-mediated endocytosis

Phagocytosis is

cell eating

Pinocytosis is

cell drinking

In phagocytosis what forms around cellular debris to create the phagosome complex?

Pseudopodes from the plasmolemma which engulfs cell debris

Once the phagosome is formed what happens?

phagosomes fuse to lysosomes fro enzymatic break down of the contents.

What other important cells have phagocytic activity?

Hint: think of immune system protection

White blood cells

Pinocytosis is an endocytosis important in

nutrient absorption from outside the cell.

Pinocytosis is a main function in which part of the human body?

lining of the small intestine

Receptor mediated endocytosis

selective mechanism for molecules and their specific binding receptors

what are some molecules involved in receptor mediated endocytosis?

Insulin, other hormones, enzymes, low desity lipoproteins (LDL)

What is the role of LDL in the body?

molecules that carry cholesterol in the blood to the body's cells

The process of R-M endocytosis is:

molecules are brought into the cells by first attaching to a receptor on the membrane before being taken into the cells in a protein coated vesicle

The cycle of R-M endocytosis ends in

Contents of the vesicles are released by binding to lysosomes and the

receptors are recycled back to plasma membrane

Some viruses and endotoxins use what mechanism to enter cells?

Receptor mediated endocytosis

Hyper =

high

Hypo =

low

Familial Hypercholeterolemia

inherited disease in which the cells lack the receptors that bind to

cholesterol binding LDLs

What is the result of hypercholesterolemia?

cholesterol cannot enter the cells and builds up in the blood,

causing hypercholesterolemia and atherosclerosis which lead to stroke or

myocardial infarction

The cytoplasm consists of

cytosol and organelles

Cytosol is made up of

viscous fluid containing water,

ions and enzymes, inclusions containing stored nutrients and pigments

The site of protein production

Ribosomes

Ribosomes consist of 2 compartments made up of

proteins and rRNA

Translation

mRNA is read by rRNA of the ribosome to find the correct amino acid to link in a chain of amino acids. The tRNA carries the specific AA coded for to the rRNA to be put into the sequence.

Rough ER

a ribosome-studded system of membrane-walled envelopes in cytosol, called cisternae

Ribosomes on Rough ER produce proteins that go where?

to ER cisternae and then are secreted by the cell in vesicles

Where are the plasmolemma proteins made?

Ribosomes

Smooth ER

No ribosomes attached

membranous system of sacs and tubules in the cytosol

Role of smooth ER

synthesis of lipids and steroids,

lipid metabolism and drug detoxification

Golgi apparatus

disc-shaped envelopes or cisternae which are bound by membrane

Role of G.A.?

sorts the products of rER and packs them in membrane bound vesicles and sends

them to their proper destination.

Also produces secretory granules and lysosomes

Mitochondria

Powerhouse of the cell

2 membranes, inner one folds into cristae

Lysosomes

spherical, membrane-walled sacs containing digestive enzymes called

Acid hydrolases.

site of intracellular digestion

Phagocytic cells have a lot of what?

Lysosomes

Tay sachs disease has what effect on the human body?

mental retardation,

blindness, spastic movements and death

within 1.5 years from birth.

What is the cause of Tay-Sachs disease?

fatal genetic lipid storage disorder in which harmful quantities of a fatty substance called ganglioside GM2 build up in tissues and nerve cells in the brain

Because there is a build of of glycolipids bc lack of lysosome activity...

glycolipids accumulate in the cell membrane specially on neurons

Gauchers disease

lack of the glucocerebrosidase enzyme causes harmful substances to build up in the liver, spleen, bones, and bone marrow. The substances prevent cells and organs from working properly.

How many types of Gauchers disease?

3

Type 1 Gauchers disease

Most common

Involves bone disease, anemia, and enlarged spleen, and thrombocytopenia.

Affects both children and adults

Type 2 Gauchers disease

usually begins in infancy with severe neurologic involvement.

This form can lead to rapid, early death.

Type 3 Gauchers disease

may cause liver, spleen, and brain problems. Patients may live into adulthood.

Symptoms of Gaucher's disease

Varies with type

Bone pain and fractures

Enlarged spleen

Enlarged liver Lung disease

Seizures

Peroxisomes

membrane walled enzyme containing sacs

What enzymes are in peroxisomes?

contain oxidase and catalase enzymes

How are oxidase enzymes used in peroxisomes?

neutralize aggressively reactive substances (free radicals) and they convert them to hydrogen peroxide,which will then be converted to O2 and H2O

What can catalases do for the body?

break down poisons like alcohol, phenol and

formaldehydes

Which parts of the body have many peroxisomes?

Kidney and Liver

Cytoskeleton

network of rods throughout the cell that work to support structure and movements

3 types of cytoskeletons

microtubules, microfilaments, intermediate filaments

Microtubules

made of tubulin

support structure/shape

organize distribution and trasport btwn organelles

Microfilaments

Made of actin

labile

actin + mysosin = contractile force for movement

mucle contraction

amoeboid mevemnets and pseudopod extension

intermediate filaments

tough, insoluble, stable protein fibers

resist tension on cell

Centrosome

spherical structure in the

cytoplasm near the nucleus. It consists of

an outer cloud of protein called: matrix

and an inner pair of centrioles

Matrix protein is involved in the elongation

of microtubules and mitotic spindle of

microtubules radiates from it in dividing

cells.

Cytoplasmic inclusions

Impermanent structures in the cytoplasm

such as lipid droplets and glycogen

containing glycosomes.

Centrioles

core of centrosome.

These are paired cylindrical bodies

perpendicular to one another and each

composed of nine triplets of microtubules.

They organize a microtubule network

during mitosis to form the spindle and asters. They also form the bases of cilia

and flagella

control center of cell

nucleus

Which cells in the human body have no nucleus?

red blood cells, skeletal muscle

Anucleated

What are the three main componenets of the nucleus?

Nuclear Envelope

Chromatin and Chromosomes

Nucleoli

Nuclear envelope

exteds through rough ER, has pores

Nucleolus

Makes ribosomes

DNA -> mRNA

transcription

Chromatin

composed of DNA and histone proteins, folded compactly and creates chromosome with an X shape

DNA

Double helix chains of nucleotides that pair

DNA nucleotide sugars

A=T

G=-C

DNA determines

our traits

nucleosome

cluster of DNA and histone

Chromosome

Single long chain of DNA tightly wound

human body has -- chromosomes

46

44 are somatic

2 are sex

Cell life cycle (stages)

1 interphase - cell growth

2 mitotic phase - leads to cell division

interphase stages

G1 - cell growth

S - DNA rep

G2 - final components neede are made

Mitotic phase

PMAT

Prophase

Asters form

Chroms formed (chromatids are identical, held together by centromere)

spindle attachments formed start to push cell

nucleoli disapear