Biology > Inheritance > Flashcards

Inheritance Flashcards

(42 cards)

Study These Flashcards
1
Q

What are the key features of DNA

A
  • DNA is a double helix strand
  • It is made up of building blocks called nucleotides
  • Nucleotides consist of a sugar (deoxyribose), a phosphate and a nitrogenous base
  • There are four types of nitrogenous bases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the four types of nitrogenous bases

A
  • Adenine (A)
  • Cytosine (C)
  • Guanine (G)
  • Thymine (T)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the pairings of nitrogenous bases

A
  • Adenine always pairs with Thymine (A and T)
  • Cytosine always pairs with Guanine (C and G)
  • This is called complementary base pairing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is RNA

A
  • A type of nucleic acid
  • The RNA nucleotides join together to form a single strand
  • RNA uses the base Uracil instead of Thymine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the differences and similarities between DNA and RNA

A

DIFFERENCES
- RNA is a single strand whereas DNA is a double helix strand
- DNA contains the base Thymine whereas RNA contains the base Uracil
- DNA has sugar called deoxyribose but RNA has ribose

SIMILARITIES
- Both have nitrogenous bases
- Both contain nucleotide

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

What are the two types of RNA

A
  • mRNA: messenger RNA it is used in transcription
  • tRNA: transfer RNA it is used in translation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a gene

A

A gene is a length of DNA that codes for a protein

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

What is a codon

A

In DNA the sequence of three bases code for a specific amino acid. The three bases are referred to as codon

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

What are chromosomes

A
  • The DNA are wrapped up in structures called chromosomes
  • Each person has two of each chromosomes (one from mother one from father)
  • Genes that control a specific characteristic are situated at the same point on each chromosome
  • So chromosomes are homologous
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is an allele

A

Allele: alternate forms of the same gene
- They code for different forms of a protein
- E.g. eye colour

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

What is a genome

A

The genome is one copy of all an organisms DNA

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

How many chromosomes does a human have

A
  • Humans have 46 chromosomes arranged in 23 pairs (2 copies of every chromosome) this
  • Human gametes are haploid cells so only have 23 chromosomes (only one coopy)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When does mitosis occur

A
  • Growth: mitosis produces new cells
  • Repair: to replace damaged or dead cells
  • Asexual reproduction: mitosis produces offspring that are genetically identical to the parent
  • All cells in the body (excluding gametes) are produced by mitosis of the zygote
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Explain the process of mitosis

A
  • When a cell gets a signal to duplicate, each chromosome in the nucleus copies itself exactly
  • This forms x - shaped chromosomes both ‘arms’ having the same DNA
  • Chromosomes line up along the center of the cell where cell fibers pull them apart
  • The cell divides into two; each new cell has a copy of each of the chromosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is mitosis

A

Nuclear division leading to genetically identical cells

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

When and where does meiosis occur

A
  • Meiosis is used to produce gametes
  • It occurs in the reproductive organs (ovaries and testes)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is meiosis

Study These Flashcards
A

Nuclear division leading 4 daughter cells that are genetically different.

18
Q

Explain the process of meiosis

Study These Flashcards
A

Each chromosome makes identical copies of itself
- First division: chromosomes pair up along the center of the cell
- Recombination occurs (sections of the maternal and paternal DNA are swapped)
- Then cell fibers will pull the pairs apart, each new cell will have one of each recombinant chromosome pair
- Second division: chromosomes will line up along the center of the cell, cell fibers will pull them apart
- A total of four haploid daughter cells will be produced, each being genetically different

19
Q

How is genetic variation in offspring ensured

Study These Flashcards
A
  • Genetic variation in gametes produced by meiosis
  • Random fertilisation of egg cells by male gametes
20
Q

What are the key stages of mitosis

Study These Flashcards
A
  • INTERPHASE: normal cell functions and DNA replication
  • PROPHASE: chromosomes condense
  • METAPHASE: chromosomes lines up in the middle
  • ANAPHASE: chromosomes pull apart
  • TELEOPHASE: nuclear membrane reforms
  • CYTOKINESIS: cells separate
21
Q

Explain the differences between mitosis and meiosis

Study These Flashcards
A

Mitosis
- 2 cells are produced
- Daughter cells are diploid
- Daughter cells are genetically identical to each other and parent cell
- One cell division occurs
Meiosis
- 4 cells are produced
- Daughter cells are haploid
- Daughter cells are genetically different from each other and parent cell
- Two cell divisions occur

22
Q

Why is variation important and why does it occur

Study These Flashcards
A
  • Variation is important for evolution to occur
  • Variation for particular characteristics can be genetic, environmental or a combination of both
23
Q

What are the two types of variation

Study These Flashcards
A
  • Continuous: e.g. height, there a smooth range of measurements (more likely to be polygenic)
  • Discontinuous: e.g. blood group, there are distinct categories no values in between (monogenic)
  • Continuous variation is often more heavily influenced by environmental factors
24
Q

What are the two types of allele and define them

Study These Flashcards
A
  • Dominant: characteristic is seen if only one copy of allele is present (represented by capital letter)
  • Recessive: needs two copies of allele for characteristic to be seen (represented by lower case letter)
25
What are the two different combinations of alleles and define them
- Homozygous: both chromosomes have the same allele (2 identical copies of allele) - Heterozygous: both contain one copy of each allele (2 different copies of an allele)
26
What is a phenotype and a genotype
- Phenotype: it is the characteristic that can be seen - Genotype: the combination of alleles the organism has
27
How should you set out a genetic cross
- State which allele is dominant and which is recessive - State parent phenotype - State parent genotype - State parent gametes - Do punnet square - State offspring genotypes - Ratio - Offspring phenotype
28
What chromosomes determine sex
- Females will have XX chromosome pair - Males will have an XY chromosome pair - The chances of having a boy or girl are 50:50
29
Describe the process of transcription
- The two strands of DNA are unzipped by breaking the weak hydrogen bonds between the base pairs - The enzyme RNA polymerase attaches to the DNA just before the gene - RNA polymerase moves along the DNA template strand - RNA nucleotides are attracted to the exposed DNA strand nucleotides by complimentary base pairing - RNA polymerase then causes the formation the formation of covalent bonds and the mRNA strand is formed - mRNA strand is ready to leave nucleus
30
Explain the process of translation
- The mRNA strand travels through the cytoplasm and attaches to the ribosome - The strand of mRNA passes through the ribosome - For every three mRNA bases (codon) the ribosome lines up one complementary molecule of tRNA, the three complimentary bases are called an anticodon - tRNA molecule transports specific amino acids to the ribosome - the tRNA molecules exit the ribosome and collect another specific amino acid - A chain of amino acids is formed called a polypeptide
31
What is a mutation
- A change in the sequence of bases in DNA - It is a rare random change in genetic material that can be inherited
32
What are the different types of mutation
- Deletion - Duplication - Substitution - Inversion
33
Explain what deletion and duplication are
- DELETION: a base in a codon is deleted effect: there is a frameshift so amino acids are different - DUPLICATION: a base is duplicated effect: causes frameshift so amino acids are different
34
Explain what substitution and inversion are
- SUBSTITUTION: one base is replaced by another base - effect: only one codon is affected - one amino acid is different - INVERSION: one codon is inverted - effect: one codon is affected - one amino acid is different - (unless it is a start codon)
35
What are the rules of natural selection
- There is a MUTATION - This causes VARIATION - This leads to SURVIVAL and REPRODUCTION - The ALLELE is passed on
36
What is co dominance
Both alleles are dominant and there isn't a recessive allele
37
What are mutagens
- Mutagens are chemicals which cause more frequent mutations, the include: - Ionising radiations (gamma rays, x-rays und UV light) - Some chemicals e.g. in tobacco
38
What is the affect of mutations
- Changes in the DNA sequence are often neutral - They can be positive (increase variation and may be beneficial if environment changes) - Or negative (protein fails to work properly)
39
What mutations are inherited
- If mutation occurs during meiosis in gamete formation the mutation will be inherited - If mutation occurs in body cell, the mutation is not inherited - Mutations increase genetic variation in a population
40
What is Darwin's theory of natural selection
- More commonly known as 'survival of the fittest' - There will be a struggle for existence because organisms over reproduce and therefore resources will be limited - Some will be better adapted to their environment than others because they vary - Those best adapted will survive and reproduce in greater numbers than the less well adapted - 'survival of the fittest'
41
How do antibiotic resistant strains of bacteria form
- A chance mutation gave some bacteria resistance to the antibiotic - These bacteria are better adapted to the environment - They survive in greater numbers - So the resistant bacteria reproduce rapidly and pass on the resistant allele - Repeated for with each generation of bacteria
42
What is a modern interpretation of Darwin's Theory
- Variation occurs due to mutations - Some individuals within a population will have features which will make them more able to survive in the environment - More likely to survive and reproduce - They will pass on their advantageous allele
Biology
flashcards
Decks in class (12)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions