3.4.1.1 DNA, genes and chromosomes Flashcards Preview

SHHS - Science - NEW AQA A-Level Biology (Year 1) > 3.4.1.1 DNA, genes and chromosomes > Flashcards

Flashcards in 3.4.1.1 DNA, genes and chromosomes Deck (25):
1

What is a gene?

A gene is a section of DNA that contains the coded information for making polypeptides and functional RNA.

2

What is the locus?

A locus is the position of a gene on a chromosome

3

What factors determine the nature and development of all organisms?

Genes and environmental factors

4

The genetic code uses 4 different DNA bases. What is the maximum number of different DNA triplets that can be made from these 4 bases?

4^3 = 64

5

What are some of the features of genetic code?

•It's degenerative •It's non-overlapping (each base only ready once) •It's universal

6

Why is genetic code described as "degenerative"?

As one amino acid can be coded for by more than one triplet

7

Why is the genetic code described as being "universal"?

In all organisms the same triplet codes for the same amino acid;

8

What are exons?

Sequence that codes for amino acids.

9

What are introns?

Non-coding sequences (not ITNRested in them)

10

Why is the genetic code described as "non-overlapping"?

Each base in the sequence is only read once

11

Describe the DNA in prokaryotic cells

•DNA molecules are shorter •They form a circle •They aren't associated with proteins (histones) •NO chromosomes

12

Describe the DNA in eukaryotic cells

•DNA molecules are longer •They form a line (linear) •They occur in association with proteins called HISTONES to form chromosomes

13

What is an allele?

Different form of a gene

14

Explain why the DNA base sequences of homologous chromosomes are almost the same.

Homologous chromosomes have the same genes At the same loci Different alleles (different forms of the same gene) usually only have a small difference in their base sequence

15

What name is given to the different forms of a gene?

Allele

16

Which 2 biological molecules make up a ribosome?

ribosomal RNA (rRNA) and Amino acids

17

Describe the shape of a replicated chromosome

2 sister chromatids held together by centromere

18

what is this a picture of?

Q image thumb

Nucleotide

19

Identify the blue circle in this nucleotide

Q image thumb

phosphate

20

Identify the green shape in this nucleotide

Q image thumb

deoxyribose (pentose sugar)

21

Indentify the pink rectangle in this nucelotide

Q image thumb

organic base - either A T G or C

22

If there is 18% adenine in a DNA sample what % will be thymine?

18

23

If there is 18% adenine in a DNA sample what % will be guanine?

32

24

name the enzyme involved in DNA replication

Helicase AND DNA polymerase

25

What is a homologous pair of chromosomes?

2 chromosomes that carry the SAME genes (different alleles)