Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology > Chapter 4- Genetics, Biodiversity, and classifcation > Flashcards

Chapter 4- Genetics, Biodiversity, and classifcation Flashcards

1
Q

What are the three components of nucleotides

A

Organic nitrogenous base, pentose sugar, and a phosphate group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the structure of DNA

A

Made up of a deoxyribose sugar, organic nitrogenous base, phosphate group.
It id double stranded and hydrogen bonds between the bases form a helix shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the role of DNA

A

DNA carries genetic information determines our inherited characteristics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are purine bases

A

Adenine and guanine both have double ring structures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are pyrimidine bases

A

Thymine, uracil, cytosine all have single rings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do nucleotides join together

A

Nucleotides join together by phosphodiester bonds formed in condensation reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the structure of RNA

A

Made up of ribose sugar, organic nitrogenous base, a phosphate group
It is single stranded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the role of RNA

A

Transfers genetic information from DNA to ribosomes from protein synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a gene

A

A sequence of bases coding for a sequence of amino acids in a polypeptide chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the location of a gene called

A

A locus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are introns

A

Introns are non-coding regions of DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are exons

A

Exons are coding regions of DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How many amino acids are there

A

20

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is DNA in eukaryotic cells different from in prokaryotic cells

A

Eukaryotic cells= DNA enclosed within a nucleus, long and linear. Associated with histone proteins to form chromosomes. Mitochondria and chloroplast contain prokaryotic-like DNA
Prokaryotic DNA= Short and circular. not associated with histones and free in the cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the genetic code

A

The order of bases on DNA, consists of codons (triplets of bases that code for a particular amino acid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Identify features of the genetic code

A

Degenerate, universal, non-overlapping

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Define a degenerate genetic code

A

More than one triplet codes for the same amino acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define a universal genetic code

A

The same bases and sequences are used by all species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Define a non-overlapping genetic code

A

Each triplet is only read once

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How many chromosomes do humans have

A

46

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is a homologous pair of chromosomes

A

A homologous pair of chromosomes consist of 2 chromosomes that carry the same gene, they are not identical as they can carry different alleles of the same gene.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is an allele

A

An allele is a different version of a gene

23
Q

What are the 2 stages of protein synthesis

A

Transcription and translation

24
Q

Compare tRNA and mRNA structure

A
  1. mRNA is longer than tRNA
  2. tRNA has an amino acid binding site and a complementary anticodon, whereas mRNA does not
  3. mRNA is linear, whereas tRNA is folded into a clover shape
25
Describe transcription
During transcription, a molecule of of mRNA is made in the nucleus. 1. DNA helicase breaks hydrogen bonds between complementary bases, and the DNA uncoils 2. One of the DNA strands is used as a template 3. Free nucleotides line up by complementary base pairing and adjacent nucleotides are joined by phosphodiester bonds. The enzyme RNA polymerase catalyses the formation of phosphodiester bonds via a condensation reaction 4. Pre-mRNA is then spliced to remove introns, which leaves just a strand of exons The mRNA then leaves the nucleus through a nuclear pore into the cytoplasm and attaches to a ribosome
26
Describe translation
1. mRNA attaches to a ribosome and tRNA brings a specific amino acid from the cytoplasm to the ribosome 2. tRNA attaches itself to mRNA by complementary base pairing 3. Another tRNA molecule brings another specific amino acid to the ribosome 4. The amino acids join via a condensation reaction by which a peptide bond is formed 5. This process is repeated as the ribosome moves along the mRNA molecule until a stop codon is reached
27
What is a genome
A genome is the complete set of genetic information contained in the cells of an organism
28
What is a proteome
The complete set of proteins that can be produced by a cell
29
What is a mutation
An alteration to the DNA base sequence that is random
30
Why might a mutation NOT lead to change in the amino acid sequence
The genetic code is degenerate, so the mutation may end up coding for the same amino acid as the original triplet Mutation may occur in the intron
31
What is a substitution mutation
When a nucleotide in the DNA base sequence is replaced by another
32
What is a deletion mutation
When a nucleotide in the DNA sequence is lost. This is more likely to be harmful and significant
33
What is a mutagenic agent
Mutagenic agents are factors that can increase the likelihood of a mutation. This includes: gamma rays, X-rays, certain chemicals,
34
What is a polyploidy chromosome mutation
Where an individual has 3 or more sets of chromosomes instead of 2
35
What is chromosome non-disjunction
When chromosomes fail to separate correctly in meiosis, which results in gametes with one more or one less chromosome than normal.
36
What is meiosis
A form of cell division that produces four genetically different haploid cells (cells with half the number of chromosomes found in the parent cell) known as gametes
37
How does meiosis differ from mitosis
Mitosis is asexual reproduction for growth and repair and produces 2 genetically identical diploid daughter cells Meiosis produces 4 genetically different haploid daughter cells
38
What happens in meiosis 1
1. Homologous chromosomes pair 2. Crossing over (exchanging of alleles) at the chiasmata 3. Cell divides into 2. Homologous chromosomes separate randomly. Each cell contains either maternal or paternal copy
39
What happens in meiosis 2
1. The chromatids of each chromosome are separated producing 4 genetically different haploid daughter cells
40
Draw a diagram to show cells after each cell of meiosis
(After meiosis 1, there should be two cells each with 2 pairs of chromosomes) (After meiosis 2, there should be 4 cells with 2 chromosomes each)
41
How does meiosis produce genetic variation
1. Crossing over during meiosis 1 (chiasmata) with the exchange of alleles 2. Independent assortment (random segregation) of homologous chromosomes and sister chromatids This results in a new combination of alleles
42
Define genetic diversity
Genetic diversity is the total number of different alleles in the population
43
Define population
A group of individuals of the same species that live in the same place at the same time and are able to breed together
44
Define a species
A species is a group of individuals that are able to breed together to produce fertile offspring
45
Define alleles
An allele is a different version of a gene
46
What advantage does high genetic diversity provide
High genetic diversity allows the ability to adapt to a change in environment and allows natural selection to occur
47
What is a niche
A niche is a species' role within an environment
48
Explain how natural selection results in the development of new characteristics
1. Random mutations results in new alleles 2. Some alleles provide an advantage in environment, making an individual more likely to survive and reproduce 3. Their offspring receive the advantageous allele and frequency continues to increase over many generations
49
What is natural selection
Natural selection is the process in which fitter individuals who are better adapted to the environment survive and pass on the advantageous allele to future generations
50
What is evolution
Evolution is the process by which the frequency of alleles in a gene pool changes over time as a result of natural selection
51
What is a gene pool
A gene pool is the collection of all the genes and alleles in a population or species
52
What is directional selection
Directional selection occurs when environmental conditions change. Individuals with phenotypes suited to the new conditions will survive and pass on their genes. Over time, the mean of the population will move towards the these characteristics
53
Give an example of directional selection
An example of directional selection is antibiotic resistance. Bacteria with a mutation that allows them to survive in the presence of antibiotics will reproduce
54
What is stabilising selection
Stabilising selection occurs when environmental conditions stay the same. Individuals closest to the mean are favoured, and any characteristics are selected against, this results in low diversity.

Biology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions