human cell structure and function

Question 1

structure of the nucleus

Answer 1

nuclear envelope double membrane
nucleoplasm
nuclear pores
chromatin
nucleolus
chromosomes

Question 2

what is the importance of nuclear pores in the nucleus membrane?

Answer 2

allows the exit of molecules from the nucleus to the cytoplasm
for example: mRNA exits the nucleus after transcription to carry out later stages of protein synthesis

Question 3

what is the nucleoplasm?

Answer 3

granular, jelly-like substance

Question 4

what is the nucleolus?

Answer 4

sit of rRNA production and ribosomes

Question 5

what is chromatin?

Answer 5

mixture of DNA and proteins, chromatin is a fine network of threads

Question 6

what are chromosomes?

Answer 6

coiled protein-bound9histones)
linear DNA

Question 7

what happens to chromatin fibres for it to become a chromosome form?

Answer 7

coiles and condenses

Question 8

List the functions of the nucleus.

Answer 8

-directs the cell’s metabolic activities
-responsible for DNA replication
-site for protein synthesis and DNA replication
-contains cell’s genetic code and genetic material

Question 9

What is the form of DNA in a non-dividing cell?

Answer 9

chromatin fibres

Question 10

What is the form of DNA in a dividing cell?

Answer 10

chromosomes

Question 11

Is the nucleus in all cells?

Answer 11

all except erythrocytes

Question 12

Is the nucleus the largest organelle?

Answer 12

yes

Question 13

Describe the structure of the plasma membrane.

Answer 13

-phospholipid bilayer
- peripheral and integral proteins
-glycolipids and glycoproteins
-cholesterol

Question 14

describe the structure of a phospholipid

Answer 14

-phosphate group “head” hydrophilic, electric charge, attracted to water

-2 fatty acid “tails” hydrophobic, no electric charge repels water

-glycerol molecule

Question 15

The function of the plasma membrane?

Answer 15

• control the passage of molecules
  -regulating the internal composition of a cell
• provides the cell with a selective barrier

Question 16

What are peripheral proteins?

Answer 16

-proteins that have a branched carbohydrate attached to itself forming a glycolipid/ glycoprotein
-embedded in the membrane but does not span across the membrane

Question 17

functions of peripheral proteins?

Answer 17

• provides mechanical support
• cell recognition
  -receptors for hormones and chemical messengers
  -provides cells with immunological identity
• cellular identification

Question 18

What is glycosylation?

Answer 18

carbohydrate attaching to proteins to form glycolipids/ glycoproteins

Question 19

What is an integral protein?

Answer 19

embedded in the membrane and spans entirely

Question 20

list the functions of integral proteins

Answer 20

-protein channels and carriers
-provide translocation of large molecules and water-soluble substances

Question 21

What is passive transport?

Answer 21

movement of substances from an area of high con to low conc down the conc gradient without using energy

Question 22

what are the types of passive diffusion?

Answer 22

• osmosis
• diffusion
  -facilitated diffusion

Question 23

definition of diffusion

Answer 23

movement of molecules from an area of high conc to low conc until equilibrium is reached

Question 24

definition of osmosis

Answer 24

movement of water molecules from an area of high conc to an area of low conc across a semi-permeable membrane

Question 25

Facilitated diffusion what does it transport?

Answer 25

- large molecules, glucose and amino acids -water-soluble substances

Question 26

types of proteins involved in facilitated diffusion?

Answer 26

transmembrane protein ( channel proteins) carrier proteins

Question 27

active transport definition

Answer 27

transport of substances against their conc gradient from an area of low to high conc using ATP as a form of energy

Question 28

Structure of mitochondria

Answer 28

- double membrane - inner membrane forms cristae - mitochondrial DNA -mitochondrial matrix -intermembrane space -ribosomes

Question 29

Function of the mitochondria

Answer 29

Site of aerobic respiration produces Atp as a form of energy

Question 30

what is found in the inner membrane of the mitochondria?

Answer 30

Atp synthase enzyme

Question 31

What is the most metabolically active in the human body?

Answer 31

liver, muscles, spermatozoa

Question 32

ribosome structure?

Answer 32

-large and small (2) subunits - composed of rRNA and proteins

Question 33

The function of the ribosome?

Answer 33

synthesis proteins during translation stage of protein synthesis from amino acids using the mRNA template

Question 34

SER function

Answer 34

- synthesis of lipids and steroid hormones -lipids used to replace plasma membranes or repair membranes

Question 35

RER function

Answer 35

- have ribosomes studded on the outer surface -synthesis of proteins

Question 36

what is the endoplasmic reticulum?

Answer 36

series of interconnecting membranous canals in the cytoplasm

Question 37

what are lysosomes?

Answer 37

small membranous vesicles which contain a variety of enzymes

Question 38

where do lysosomes come from?

Answer 38

they're pinched off from the Golgi apparatus

Question 39

what different functions do the enzymes in the lysosomes have?

Answer 39

- in white blood cells they digest foreign materials (microbes) -can break down large polymers like DNA carbohydrates proteins

Question 40

approximately how many types of cells are there?

Answer 40

200

Question 41

what are chondrocytes?

Answer 41

cartilage cells

Question 42

what are myocytes?

Answer 42

muscle cells

Question 43

what are thrombocytes?

Answer 43

platelet cells

Question 44

what are leukocytes?

Answer 44

white blood cells

Question 45

what are erythrocytes?

Answer 45

red blood cells

Question 46

what are neuroglial cells?

Answer 46

-provide developmental, physiological, and metabolic support for neurons -responsible for maintaining homeostatic control and immune surveillance in the nervous system.

Question 47

what are neurons?

Answer 47

nerve cells

Question 48

stem cells?

Answer 48

raw cells from which specialised cells are differentiated from

Question 49

what are some of the general cell actions and functions?

Answer 49

-reproduce -nourishment -create and maintain -excrete -respiration -growth -movement