inheritance Flashcards
What is the entirety of an organism’s DNA called?
The genome
The genome contains all the genetic information of an organism.
What is a gene?
A section of a molecule of DNA that codes for a particular sequence of amino acids
What do genes control?
Characteristics by coding for proteins that play important roles in cellular functions
What are chromosomes?
Structures formed by the supercoiling of DNA double helix in the nucleus during cell division
How many pairs of chromosomes do ordinary human body cells contain?
23 pairs, totaling 46 chromosomes
This is referred to as the diploid number (2n).
Define alleles.
Variations of the same gene that exist in alternative forms
What is the phenotype?
The observable characteristics of an organism
What is the genotype?
The combination of alleles that control each characteristic
What is a dominant allele?
An allele that only needs to be inherited from one parent for the characteristic to show up in the phenotype
What is a recessive allele?
An allele that needs to be inherited from both parents for the characteristic to show up in the phenotype
What does it mean if an individual is homozygous?
They have two identical alleles for a gene
What is polygenic inheritance?
Inheritance of characteristics controlled by multiple genes
Give an example of polygenic inheritance.
Eye colour
Eye colour is influenced by several genes, leading to a range of phenotypes.
What is monohybrid inheritance?
Inheritance of characteristics controlled by a single gene
What is a Punnett square?
A genetic diagram used to show possible combinations of alleles in offspring
What do family pedigree diagrams trace?
The pattern of inheritance of a specific characteristic through generations of a family
What shapes represent males and females in family pedigrees?
Males are squares, females are circles
What are sex chromosomes for females and males?
Females: XX, Males: XY
What is mitosis?
Nuclear division giving rise to genetically identical cells
What is the purpose of mitosis?
Growth, repair of damaged tissues, replacement of cells, asexual reproduction
What is meiosis?
A type of nuclear division that produces cells that are genetically different
What are gametes?
Haploid cells produced during meiosis
What is random fertilization?
The process where any male gamete can fuse with any female gamete, creating genetic variation
What are some examples of genetic variation in humans?
- Blood group
- Eye colour
- Gender
- Ability to roll tongue
- Earlobe attachment
What is genetic variation between gametes?
Each gamete carries substantially different alleles
This variation is critical for genetic diversity in offspring.
What happens during fertilisation?
Any male gamete can fuse with any female gamete to form a zygote
This random fusion creates genetic variation between zygotes.
What are examples of genetic variation in humans?
- Blood group
- Eye colour
- Gender
- Ability to roll tongue
- Earlobe attachment
These traits are influenced by genetic factors.
Define a diploid cell.
A cell that contains two complete sets of chromosomes (2n)
Nearly all human body cells are diploid.
What is the chromosome count in a diploid human cell?
46 chromosomes (23 pairs)
These chromosomes contain the DNA necessary for cell function.
Define a haploid cell.
A cell that contains one complete set of chromosomes (n)
Haploid cells are involved in sexual reproduction.
What are gametes in humans?
- Female egg
- Male sperm
These are haploid cells necessary for reproduction.
What is variation in a species?
Differences between individuals of the same species
Variation can be influenced by genetic and environmental factors.
What can cause environmental variation?
- Climate
- Diet
- Accidents
- Culture
- Lifestyle
These factors can affect characteristics of species.
What is discontinuous variation primarily caused by?
Genetic variation alone
This type of variation results in distinct categories.
What is continuous variation usually influenced by?
A combination of genetic and environmental causes
Examples include height, which is affected by both genes and nutrition.
Define mutation.
Rare, random changes that occur in the sequence of DNA bases in a gene or chromosome
Mutations can sometimes lead to changes in protein function.
What is Darwin’s Theory of Evolution by Natural Selection?
Evolutionary change occurs through natural selection, where advantageous traits increase survival and reproduction
This theory is fundamental to understanding evolution.
What is the process of natural selection?
- Variation in a species
- Survival of the fittest
- Reproduction of advantageous traits
- Increase in frequency of advantageous traits
This process explains how species evolve over generations.
What is an example of natural selection?
The color variation in peppered moths
This illustrates how environmental changes can affect survival.
How does antibiotic resistance occur?
- Random mutation creates a resistance allele
- Non-resistant bacteria die off
- Resistant bacteria reproduce
- Resistance allele frequency increases
This process shows natural selection in action.
True or False: Antibiotic resistance can be treated with the same antibiotic once resistance develops.
False
Different antibiotics may be needed to treat resistant infections.
What is Darwins evolution?
A change in the inherited characteristics of a population over time through natural selection, potentially resulting in a new species.
What role do mutations play in evolution?
They provide variation between organisms, and if beneficial, increase the chances of survival and reproduction.
Define ‘survival of the fittest’.
The concept that organisms with advantageous mutations are more likely to survive to breeding age.
What is genetic variation?
The differences in DNA among individuals of the same species within a population.
What is mitosis?
A type of cell division where one cell divides to form two identical daughter cells.
What occurs during Interphase in the cell cycle?
- The cell grows
- Organelles increase in number
- Protein synthesis occurs
- All chromosomes are replicated
- Energy stores are increased
What happens in Stage 2 of mitosis?
The chromosomes line up at the equator, and spindle fibers pull each chromosome to opposite poles.
What occurs in Stage 3 of mitosis?
Two identical daughter cells form when the cytoplasm and cell membranes divide.
What are the purposes of mitosis?
- Growth and development
- Replacing damaged cells
- Asexual reproduction
How are the two strands of DNA held together?
By hydrogen bonds between pairs of bases: adenine with thymine, and cytosine with guanine.
Fill in the blank: The characteristic shape of replicated chromosomes is _______.
‘X’ shape
