Molecules Of Life

Question 1

Recall the chromosomes in the nucleus:

Answer 1

Carry coded information in the form of genes

Are made of a molecule called DNA

Question 2

What is the information in the genes in form of?

Answer 2

Coded instructions called the genetic code

Question 3

What does the genetic code control?

Answer 3

Cell activity and consequently some characteristics of the organism

Question 4

What does DNA control?

Answer 4

The production of different proteins

Question 5

What are proteins needed for?

Answer 5

Growth and repair of cells

Question 6

Who worked out the structure of DNA?

Answer 6

Two scientists called Watson and Crick

Question 7

Explain why liver and muscle cells have large numbers of mitochondria?

Answer 7

They have a high energy requirement

Question 8

Are ribosomes easily seen?

Answer 8

No they are too small to be seen with the light microscope

Question 9

Where are ribosomes found?

Answer 9

In the cytoplasm and are the site of protein synthesis

Question 10

Describe the structure of DNA

Answer 10

Two strands coiled to form a double helix, each strand containing chemical bases, of which these are four different types, with cross links between the strands formed by pairs of bases.

Question 11

Describe chromosomes

Answer 11

Long, coiled molecules of DNA, divided up into regions called genes

Question 12

Recall that each gene:

Answer 12

Contains a different sequence of bases

Codes for a particular protein

Question 13

Where are proteins made?

Answer 13

In the cytoplasm

Question 14

Understand why a copy of the gene is needed

Answer 14

The gene itself cannot leave the nucleus

Question 15

What are the four bases of DNA

Answer 15

A
T
C
G

Question 16

Describe the complimentary base pairs

Answer 16

A - T

G - C

Question 17

Explain how protein structure is determined by the DNA base code

Answer 17

• the base sequence determines amino acid sequence

- each amino is coded for by a sequence of 3 bases

Question 18

Explain how the code needed to produce a protein is carried from the DNA to the ribosomes by a molecule called mRNA

Answer 18

1. mRNA constructed from DNA template in nucleus
2. mRNA carries code from original DNA into the cytoplasm and becomes attached to a ribosome
3. Ribosome ‘translates’ the code on mRNA and constructs a sequence of amino acids
4. Amino acids linked together as a long chain protein,which is released from the ribosomes to carry out its function

Question 19

Explain how DNA controls cell function by controlling the production of proteins, some of which are enzymes

Answer 19

When a cell needs to produce proteins of a particular type, certain genes will be ‘switched on’. These genes and their resulting proteins determine the characteristics of cells.

Question 20

Describe how Watson and Crock used data from other scientists to build a model of DNA

Answer 20

X-ray data showing that there were two chains wound in a helix
Data indicating that the bases occurred in pairs

Question 21

Explain why new discoveries, such as Watson and Crick’s, are not accepted or rewarded immediately

Answer 21

The importance of other scientists repeating or testing the work

Question 22

Where does respiration occur?

Answer 22

In the mitochondria providing energy for life processes