Preview of the cell and cell types

Question 1

What are cells classified into?

Answer 1

Prokaryotic cells

Eukaryotic cells

Question 2

define a cell.

Answer 2

Basic unit of structure and function in the body.

Question 3

why are cells so complex?

Answer 3

Cells are highly complex and well organized
They manage hundred of thousands of complex reactions almost every second. Cell is capable of independently sustaining and reproducing itself.

Question 4

name the different parts of a cell.

Answer 4

Plasma membrane
Cytoplasm
Nucleus
Endoplasmic reticulum
Golgi apparatus
Centrosome
Mitochondria
Ribosome
Lysosome
Peroxisome
Cytoskeleton
Vacoule

Question 5

discuss prokaryotic cells.

Answer 5

Prokaryotic cells are unicellular organisms that lack organelles or other internal membrane-bound structures

therefore they do not have a nucleus but instead generally have a single chromosome which is a piece of circular double-stranded DNA located in an area of the cell called the nucleoid

Question 6

what is a nucleoid and which type of cell do we find it in and what is found in the nucleoid?

Answer 6

Nucleoid is a DNA region in prokaryotic cells. Contains a single circular DNA chromosome

Question 7

define eukaryotic cell and give examples of organisms that have this type of cell.

Answer 7

Eukaryotic cells are cells that contain a nucleus and organelles and are enclosed by a plasma membrane.
E.g protozoa, fungi, plants and animals.

Grouped in a biological domain called Eukaryota.

Question 8

what is the name of the group into which organisms with eukaryotic cells are grouped?

Answer 8

Eukaryota

Question 9

write as many differences between prokaryotic vs eukaryotic.

Answer 9

Prokaryotic cells:
have no nucleus, have no membrane-enclosed organelles, have single chromosome, no streaming in the cytoplasm, cell division without mitosis, simple flagella, smaller ribosomes, simple cytoskeleton, no cellulose in cell walls, no histone proteins.

Eukaryotic cells:
they do have a nucleus, they have membrane-enclosed organelles, they have chromosomes in pairs, they have streaming in the cytoplasm, their cell division is by mitosis, they have complex flagella, larger ribosomes, they have a complex cytoskeleton, cellulose in the cells, and DNA is bound to histone protein.

Question 10

define cell organelle.

Answer 10

Cell organelles are distinct structures inside cells.

May be enclosed by one membrane, two or no membrane.

Question 11

what is the function of cell organelles?

Answer 11

They function to compartmentalize biochemical reactions. With the enzymes and substrates for a reaction in the same compartment. The products of reactions are passed on to next enzyme by adding that enzyme to the compartment. Enables maintenance of different conditions to the rest of the cell.

Question 12

what are the components of the cell membrane?

Answer 12

Lipid -major component, PREVENTS the passage of hydrophilic(Water Soluble Molecules)
Proteins – ALLOW movement of water-soluble molecules
Carbohydrates on surface attached to lipids/proteins:
O Cell-to-cell interaction
O Cell recognition

Question 13

what is the basic structure that all cell membranes have in common?

Answer 13

Proteins suspended in a double layer of phospholipids
Maintains integrity of cells
Separates fluid and contents inside from those outside

Question 14

on the cell membrane are found membrane proteins, what are their functions?

Answer 14

1. Transport
2. Enzymatic activity
3. Receptors for signal transduction
4. Intercellular joining
5. Cell to cell recognition
6. Attachment to the cytoskeleton and extracellular matrix

Question 15

what are the crucial functions of the plasma cell membrane?

Answer 15

Isolates cell’s contents from the external environment

Regulates the exchange of essential substances

Regulates biochemical reactions

Allows communication between cells

Creates attachments within and between cells

Question 16

what is meant by cytoplasm?

Answer 16

Is the cellular material between the plasma membrane and the nucleus
Site where most cellular activities are accomplished

Question 17

what cellular activities occur in the cytoplasm?

Answer 17

The cytoplasm is the site of most cellular activities including metabolism, cell division, and protein synthesis. Glycolysis is also an example

Question 18

the cytoplasm consists of three major elements, what are they?

Answer 18

1. The cytosol- is the viscous, semitransparent fluid in which the cytoplasmic elements are suspended.
2. Cytoplasmic organelles- metabolic machinery of the cell; some synthesize proteins, others package those proteins
3. Inclusions- chemical substances that may or may not be present, depending on cell type. Examples include stored nutrients, such as the glycogen granules abundant in liver and muscle cells; lipid droplets common in fat cells; pigment (melanin) granules seen in certain cells of skin and hair, and crystals of various types.

Question 19

what are cytoplasmic organelles? what does it mean to be membranous and non-membranous organelle?

Answer 19

Specialized cellular compartments, each performing its own function to maintain the life of a cell.

Non-membranous organelles –lack membrane

Most organelles are bounded by a membrane similar to a plasma membrane and this membrane enables membranous organelles to maintain an internal environment different from that of the surrounding cytosol.

Question 20

what is a mitochondrion and what are its functions?

Answer 20

Are threadlike or sausage-shaped membranous organelles.

A powerhouse of the cell providing most of its ATP supply

Question 21

list organelles found in the cytoplasm.

Answer 21

Mitochondria
Peroxisomes
Lysosomes
Endoplasmic reticulum
Golgi apparatus

Question 22

describe the structure and components of mitochondria.

Answer 22

Enclosed by two membranes; the outer membrane is smooth and featureless and the inner membranes folding inwards forming cristae
Cristae protrude to the matrix (gel-like substance).
Contain their own DNA and RNA and are able to reproduce themselves.
Contain their own ribosomes, the 70S, rRNA, and tRNA.
Self-replicating in response to cell need
Support endosymbiotic theory.

Question 23

what are ribosomes and what are they responsible for in the cell?

Answer 23

They are small, dark-staining granules composed of proteins and a variety of RNA called ribosomal RNA.
Some ribosomes float in the cytoplasm and others attached to a membrane called the rough endoplasmic reticulum.
Ribosomes are protein synthesis machinery

Question 24

ribosome is a combination of things big and small what are they called?

Answer 24

Consist of the 50s and 30s

Question 25

what is Golgi apparatus and what is its major function?

Answer 25

Consist of stacked and flattened membranous sacs, shaped like a hollow dinner plates Is the principal traffic director for cellular proteins Major function: is to modify, concentrate and package the proteins and lipids made at the rough ER.

Question 26

why do we need lysosomes in the cell (function)? what do they contain inside that helps them carry out their function?

Answer 26

Lysosomes function as a cell’s “demolition crew” by Digestive particles are taken in by endocytosis, particular ingested bacteria, viruses, and toxins Degrading worn-out or nonfunctional organelles Performing metabolic functions, such as glycogen breakdown and release Breaking down non-useful tissues, such as the webs between the fingers and toes of a developing fetus and the uterine lining during menstruation Breaking down bone to release calcium ions into the blood

Question 27

what is endoplasmic reticulum?

Answer 27

Is an extensive system of interconnected tubes and parallel membranes enclosing fluid filled cavities or cisternae that coils and twists through the cytosol

Question 28

what is the importance of rough endoplasmic reticulum?

Answer 28

Rough ER- its ribosomes manufacture all proteins secreted from cells; it is abundant and well developed in most secretory cells, antibody-producing plasma cells and liver cells which produce blood proteins

Question 29

what does the smooth ER do?

Answer 29

it is continuation of rough ER; no role in protein synthesis.

Question 30

where are lysosomes found most abundantly? why?

Answer 30

Are spherical membranous organelles containing digestive enzymes Large and FOUND MOST abundantly in phagocytes Phagocytes eat stuff and must digest it.

Question 31

what are the three types of rods in the cytoskeleton?

Answer 31

Microtubules- hollow tubes; movements of organelles; forms cilia, flagella, centrioles Microfilaments- actin; cell movements; support of cells Intermediate filaments

Question 32

discuss the function of the cytoskeleton .

Answer 32

Elaborated series of rods running through the cytosol. Its acts as a cell’s bones, muscles and ligaments by supporting cellular structures and providing the machinery to generate various cell movements

Question 33

--- are made up of fibrous proteins that are organized into tough, rope like assemblages (coiled coils)?

Answer 33

Intermediate filaments

Question 34

what are intermediate filaments' major structural functions?

Answer 34

have two major structural functions: They stabilize cell structure. They resist tension.

Question 35

The microfilament, part of the cytoskeleton. discuss.

Answer 35

Thinnest elements of the cytoskeleton Each cell has its own unique arrangement of microfilaments Attached to CAMs – responsible for the crawling movements of amoeboid motion Responsible for membrane changes that accompany endocytosis and exocytosis Cell moved by: Fila podia- extension thin finger-like structure Lamellipodia-extension thin sheet Both utilize lots of f-actin and more gets added in the front as the cell moves Myosin pushes fibres against cell membrane to move cell forward Microfilament form basis of microvilli and stereo cilia

Question 36

microtubules? discuss

Answer 36

Microtubules are long, hollow cylinders made up of many molecules of the protein tubulin. Consists of two subunits: alpha-tubulin and beta-tubulin Microtubules have two roles: They form a rigid internal skeleton. They act as a framework along which motor proteins can move and organize structures in the cell. Microtubules are directional.Often originate from a center close to the nucleus: the centrosome

Question 37

what are the 2 types of axonal transport? explain

Answer 37

Anterograde transport -From cell body to synapse. Retrograde transport -Unwanted substances from synapse to cell body for destruction by lysosomes.

Question 38

What does the nucleus contain that is so important?

Answer 38

The nucleus​ is a membrane-bound structure that contains the cell’s hereditary information and controls the cell’s growth and reproduction.

Question 39

discuss the nucleus. where is it found? where is not found? what in and around the nucleus?

Answer 39

Present in all eukaryotic cells, they may be absent in few cells like the mammalian RBCs. It is mostly round, it may be oval, disc-shaped depending on the type of cell. It is the command center of a eukaryotic cell and is commonly the most prominent organelle in a cell.

Question 40

what are the functions of the nucleus?

Answer 40

It controls the heredity characteristics of an organism. It maintains cellular metabolism by controlling the synthesis of particular enzymes. It is responsible for DNA replication, cell division, growth, and differentiation. Stores heredity material in the form of deoxyribonucleic acid (DNA) strands. Also stores proteins and ribonucleic acid (RNA) in the nucleolus It is a site for transcription process in which messenger RNA (mRNA) are produced for protein synthesis. It helps in exchange of DNA and RNA (heredity materials) between the nucleus and the rest of the cell. Nucleolus produces ribosomes and are known as protein factories. It also regulates the integrity of genes and gene expression.

Question 41

- list the fundamental properties of the cell.

Answer 41

Cells are highly complex and organized Cells possess a genetic program and the means to use it. Cells are capable of producing more of themselves Cells acquire and utilize energy Cells carry out a variety of chemical reactions Cells engage in mechanical activities Cells are able to respond to stimuli Cells are capable of self-regulation Cells evolve

Question 42

- who performed the first culture of human cells? when? what type of cells did he culture?

Answer 42

1951 George Gey of Johns Hopkins University • Malignant tumour from Henrietta Lacks –HeLa cells Still cultured in labs today Cells cultured in the lab (in vitro) are easier to study than cells in the body (in vivo)

Question 43

- what do we mean by cells are complex? what is the consequence of this complexity?

Answer 43

Complex –consisting of many different and connected parts The more complex a structure, the greater the number of parts that must be in their proper place, the less tolerance of errors in the nature and interactions of the parts, and the more regulation or control that must be exerted to maintain the system.

Question 44

- what do we mean by organized? discuss

Answer 44

Organized –arranged in a systematic way the organization of these molecules into giant polymers; and the organization of different types of polymeric molecules into complexes, which in turn are organized into subcellular organelles and finally into cells. As will be apparent, there is a great deal of consistency at every level. Each type of cell has a consistent appearance when viewed under a high-powered electron microscope; that is, its organelles have a particular shape and location, from one individual of a species to another. Similarly, each type of organelle has a consistent composition of macromolecules, which are arranged in a predictable pattern. Consider the cells lining your intestine that are responsible for removing nutrients from your digestive tract

Question 45

- whats the genetic program cells possess?

Answer 45

Organisms are built according to information encoded in a collection of genes, which are constructed of DNA. Information is packaged into a set of chromosomes that occupies the space of a cell nucleus. Genes are more than storage lockers for information: they constitute the blueprints for constructing cellular structures, the directions for running cellular activities, and the program for making more of themselves.

Question 46

- how do cells reproduce themselves?

Answer 46

Occurs by division: | • Genetic material is duplicated, then the “mother” cell divides into 2 “daughter” cells

Question 47

- how do cells acquire and use energy? why do they convert it to another type of energy? what type of energy is this?

Answer 47

In plant cells, chloroplasts capture light energy and convert it to energy-rich carbohydrates e.g. glucose, starch Most animal cells receive energy as glucose Broken down to a more usable form –ATP

Question 48

- what catalyses chemical reactions in the cells? what do these reactions represent?

Answer 48

Enzymes = molecules which catalyze these chemical reactions All chemical reactions within a cell represent that cells’ metabolism

Question 49

- what mechanical activities do cells perform? give examples.

Answer 49

Transport materials from place to place E.g. endocytic vesicles can be transported to the lysosome Assemble/disassemble structures E.g. actin cytoskeleton in eukaryotes and PG layer in prokaryotes Movement of the cell itself E.g. phagocytes leave the bloodstream via a process called Diapedesis and enter the tissues at the site of a wound

Question 50

- how do unicellular protists respond to stimuli?

Answer 50

moves towards a source of nutrients

Question 51

- how do multicellular organisms respond to stimuli?

Answer 51

Most cells are covered with receptors which respond to environment triggers Detect hormones, growth factors, extracellular material, substances on the surface of other cells May trigger a change in metabolic activity, movement from 1 place to another, or apoptosis of the cell

Question 52

- why do all cellular processes require constant regulation?

Answer 52

All cellular processes require constant regulation E.g. failure to correct a mistake in DNA replication may cause a damaging mutation or a breakdown in the cells growth regulation system causing it to become cancerous

Question 53

- how do cells evolve?

Answer 53

Mutations can occur naturally in DNA over time Harmful –selected against –cell dies Beneficial –survival or reproductive advantage, will dominate population over time

Question 54

- what type of macromolecule does not self-replicate?

Answer 54

Polypeptides

Question 55

only --- can self replicate.

Answer 55

nucleic acids

Question 56

- RNA can catalyse several reactions give example?

Answer 56

incl. polymerization of nucleotides | i. e. RNA = template and catalyst for it’s own replication

Question 57

- how did early cells obtain nutrients ?

Answer 57

Early cells Lived in a sea of organic molecules Obtained nutrients directly from the environment

Question 58

- Present cells perform --- which is a mechanism for energy where glucose is converted to ATP?

Answer 58

Glycolysis:(anaerobic) | •Mechanism for energy in preformed glucose to be converted to ATP

Question 59

- oxidative metabolism is also called? discuss

Answer 59

Requires O2 More efficient: up to 36 ATP instead of 2 for anaerobic glycolysis Most modern cells use oxidative metabolism as their main source of energy

Question 60

- What is the endosymbiotic theory? incl. 5 points

Answer 60

describes how a “composite” cell could evolve from 2 or more simpler separate cells living in a symbiotic relationship with each other 1. Start with two independent bacteria 2. One bacterium engulfs the other 3. One bacterium now lives inside the other 4. Both bacteria benefit from the arrangement 5. The internal bacteria are passed on from generation to generation

Question 61

- break down anaerobic heterotrophic.

Answer 61

Earliest prokaryotes are thought to be anaerobic heterotrophic cells •Anaerobic = derived energy from food matter without using molecular oxygen (O2) •Heterotrophic= digest organic material into inorganic molecules that are used for synthesis of organic substances

Question 62

- give 4 points as evidence for the endosymbiotic theory

Answer 62

1. Mitochondria and chloroplasts have their own circular DNA similar to that found in bacteria 2. Mitochondria and chloroplasts are surrounded by 2 membranes –the inner one from engulfed bacteria and the outer one from the cell membrane of the host 3. Mitochondria are about the same size as bacteria 4. Mitochondria are genetically related to purple bacteria; chloroplasts are genetically related to photosynthetic bacteria

Question 63

- what are the 3 principles of the cell theory?

Answer 63

All organisms are composed of one or more cells. The cell is the structural unit of life Cells can arise only by division from a pre-existing cell

Question 64

- modern eukaryotic cells developed via the --- theory.

Answer 64

endosymbiotic theory

Question 65

Transport along microtubules.

Answer 65

Microtubules form the tracks for cellular movement e.g. Nerve cells Synapse where chemicals are released is far from the nucleus and cell body where the chemicals are produced Synapse does not contain ribosomes for protein synthesis i.e. Proteins and membrane compartments required in synapse Produced in cell body and transported along microtubules to synapse – Fast axonal transport

Question 66

What does the cell theory state?

Answer 66

All living things are made up of cells. Cells are the basic units of structure and function in living things. Living cells come only from other living cells.