Genetics And Division Flashcards Preview

Biology > Genetics And Division > Flashcards

Flashcards in Genetics And Division Deck (43):
1

What is DNA?

A double helix, each of the two DNa strands is made up of small molecules called nucleotides

2

Name the four bases in DNA

(A) adenine
(C) cytosine
(G) guanine
(T) thymine

3

What does each base of DNA form?

Hydrogen bonds to a base of the other side, this keeps the two strands tight together

4

Which two bases join together?

Adenine (A) and thymine (T)
Cytosine (C) and guanine (G)

5

Why are the bases in DNA a certain pair?

They complement each other in shape

6

A section of DNA that codes for a particular protein is called

A gene

7

How do proteins have different functions?

The chains of amino acids are different orders and numbers to give each protein a different shape

8

What decides the order of amino acids in a protein?

The order of the bases in a gene

9

Where are DNA molecules found?

In the nucleus of a cell

10

Where does protein synthesis happen?

In the cytoplasm at organelles called ribosomes

11

What is the copy of a gene made from?

From a molecule called messenger RNA

12

What is RNA made from?

Nucleotides

13

What does a cell do when it needs a particular protein?

Makes a copy of the gene that's smaller than the DNA so it can move in to the cytoplasm where it's used to make the protein

14

There is no thymine (T) in RNA, so what replaces it to join adenine (A)?

Uracil (U)

15

What happens when the bases on the RNA nucleotides have paired up with the bases on the DNA strand?

The RNA nucleotides join together to make an mRNA molecule.

16

What is DNA made up of?

Nucleotides containing bases

17

What do three bases in a row code for?

One amino acid

18

How many bases code for one amino acid?

Three (a triplet)

19

The order of the bases in the DNA of a gene determines what?

The order of bases in its mRNA copy, and that determines the order of amino acids in a protein

20

What are mutations?

Changes to the base sequence of DNA

21

What can a change in the amino acids cause?

A different protein to be produced, sometimes it can be harmful

22

What are mutagenic agents?

Factors that increase mutations, such as UV radiation in sunlight

23

How can mutations cause cancer?

Cell division is controlled by proteins, is mutations occur in the genes for these proteins, they can alter so they no longer work. This can lead to uncontrolled cell division, developing a tumour (cancer)

24

How can mutations cause genetic disorders?

Mutations that result in altered genes and proteins can be inherited such as cystic fibrosis

25

Where and in what cells is DNA found?

In the nucleus of eukaryotic cells

26

How many homologous pairs of chromosomes do humans have?

23

27

What are alleles?

Different versions of a gene

28

Are homologous pairs of chromosomes identical? Why?

Yes, they are the same size and carry the same gene

29

Why is the name of the region where two identical chromatids are joined?

Centromere

30

What is mitosis needed for?

Growth and repair

31

What type of reproduction involves mitosis?

Asexual

32

What happens in asexual reproduction?

A single organism produces offspring by dividing into two organisms, all offspring are genetically identical to each other and to the parent

33

Explain what happens in mitosis (briefly)

The DNA copies itself, then divides once

34

What are the 5 stages of mitosis?

Interphase
Prophase
Metaphase
Anaphase
Telophase

35

Explain interphase

Before the cell divides, each chromosome much replicate so each new cell has a full copy of DNA

36

Explain prophase

Mitosis can now begin, each DNA molecule becomes compact, so the chromosomes can now be seen by the microscope and appears as two chromatids

37

Explain metaphase

The nuclear membrane breaks down and the chromosomes line up along the middle of the cell

38

Explain anaphase

The centromeres split and the chromatids separate

39

Explain telophase

A nuclear membrane forms a round each set of chromatids and the cytoplasm divides

40

What production is meiosis?

Sexual

41

Describe sexual reproduction

The offspring are genetically different from each other and their parents. This produces variation

42

How many cells are produced when a cell divides by mitosis?

2

43

What are gametes

Sex cells