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Flashcards in B3a-molecules Of Life Deck (20)
1

Why do liver and muscle cells have large numbers of mitochondria?

They need lots of energy
Liver cells-carry out metabolic reactions
Muscle cells- contract

2

What do chromosomes do?

Carry coded information in the form of genes
Made of a molecule called DNA

3

What are proteins needed for?

Growth and repair of cells

4

What is the structure of DNA?

-Two strands coiled to form double helix
-Each strand contains chemical bases
-four bases: A T C G
-crosslinks between strands formed by pairs of bases

5

What are the complementary base pairings?

A T
G C

6

What is the genetic code?

Information in genes in the form of coded instructions

7

What are chromosomes?

Long coiled molecules of DNA divided up into regions called genes

8

What does the genetic code control?

Controls cell activity
Characteristics of the organism

9

What does each gene do?

Contains a different sequence of bases
Codes for a particular protein

10

How is protein structure determined by DNA base code?

Base sequence determines amino acid sequence
Each amino acid is coded for by a sequence of 3 bases

11

What happens in the mitochondria?

Respiration takes place
Respiration provides energy for cell processes

12

Where are proteins made?

In the cytoplasm

13

Why is a copy of the gene needed?

Gene itself cannot leave the nucleus
Its really big

14

How is the code needed to produce a protein carried from DNA to ribosomes?

-proteins made in cytoplasm by ribosomes
-ribosomes use code in DNA
-mRNA made by copying code from DNA
-mRNA carries code between two

15

What are ribosomes?

-tiny structures
-in the cytoplasm and are the site of protein synthesis
-too small to be seen with light microscope

16

How did Watson and crick discover structure of DNA?

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

17

Why was Watson and cricks work not accepted immediately?

Other scientists need to repeat work first and make sure results are reliable

18

How does DNA control cell function?

-cells have different functions because they make different proteins
-switched on genes determine the function of the cell
Eg genes for muscle cell proteins switched on = muscle cell

19

What are switched off genes?

The proteins they code for aren't produced

20

What are switched on genes?

The proteins they code for are produced