Unit 7: Inheritance and Variation Flashcards
What do all organisms inherit from their parents?
Traits or observable characteristics
Inherited traits can include physical features, behaviors, and risks of diseases.
What are inherited traits found in?
Genes
Genes are pieces of hereditary material passed from parents to offspring.
What are genes a part of?
Chromosomes
Chromosomes are structures found in the nucleus of the cell.
Where are chromosomes located in multicellular organisms?
In the nucleus of the cell
Chromosomes contain DNA and genes.
What is DNA short for?
Deoxyribonucleic acid
DNA is a long molecule that makes up chromosomes.
What is a gene?
A specific stretch of DNA
Each chromosome contains many genes.
How many genes does each chromosome contain?
Many genes
Each gene is a specific segment of the DNA molecule.
What is the typical number of chromosomes in a human body cell?
46
This number represents the diploid set of chromosomes in humans.
How are human chromosomes organized?
Into 23 pairs
Each pair consists of homologous chromosomes.
What are homologous chromosomes?
Paired chromosomes that are the same size and shape
They contain the same genes but may have different alleles.
What do homologous chromosomes contain?
The same genes
They may vary in terms of alleles, which are different versions of the same gene.
What is a karyotype?
A visual representation of an organism’s sets of chromosomes
It arranges pairs of homologous chromosomes next to each other.
What is the purpose of arranging homologous chromosomes in a karyotype?
To see if there are any differences that may lead to a genetic condition
This facilitates the identification of chromosomal abnormalities.
True or False: Homologous chromosomes can have different alleles.
True
Different alleles represent variations of the same gene.
Fill in the blank: The 46 chromosomes in a human cell can be organized into _______.
23 pairs
Each pair consists of homologous chromosomes.
What are genes?
Specific stretches of a chromosome’s DNA molecule
What are the building blocks of DNA?
Nucleotides
How many types of nucleotides are there in DNA?
Four types
What are the shortened names of the four types of nucleotides?
- A
- C
- T
- G
What do the letters A, C, T, and G stand for?
- A: Adenine
- C: Cytosine
- T: Thymine
- G: Guanine
What connects the nucleotides in a gene?
A specific order
What are proteins?
Molecules that carry out many different functions in cells
What functions do some proteins provide in cells?
- Structure for the cell
- Help carry out chemical reactions
What are proteins made up of?
Amino acids
How are amino acids in a protein connected?
In a specific order
What determines a protein’s 3D structure and function?
The order of amino acids
How does the cell build proteins?
Using instructions found in genes
What determines the order of amino acids in proteins?
The order of nucleotides in a gene
Can an organism produce many different proteins?
Yes, because it has many different genes
What do the proteins produced by an organism affect?
The organism’s traits
What is a mutation?
A mutation is any change to the nucleotide sequence of a DNA molecule.
Mutations can arise during DNA copying or due to environmental factors.
What can a mutation in a gene change?
It can change the structure and function of the protein encoded by that gene.
This alteration can subsequently affect an organism’s traits.
What are the three classifications of mutations based on their effects on organisms?
Harmful, beneficial, or neutral.
Each classification has different impacts on health and survival.
What are harmful mutations?
Mutations that have negative effects on an organism’s health and survival.
Examples include inherited disorders such as sickle cell anemia and cystic fibrosis.
What are beneficial mutations?
Mutations that have positive effects on an organism’s health and survival.
For example, some people have mutations that lower their risk of developing type 2 diabetes.
What are neutral mutations?
Mutations that have no observable effect on an organism’s traits.
For instance, some gene mutations do not lead to amino acid changes and do not affect protein function.
Fill in the blank: A mutation can be considered _______ to an organism.
harmful, beneficial, or neutral.
True or False: All mutations affect an organism’s traits.
False.
Neutral mutations do not affect traits.
What type of organisms are primarily diploid?
Many sexually reproducing organisms
Diploid organisms have two sets of chromosomes.
How are chromosomes organized in diploid organisms?
Into homologous pairs
Homologous pairs consist of one chromosome from each parent.
What are gametes produced by diploid organisms?
Egg or sperm cells
Gametes are essential for sexual reproduction.
What is the chromosome set in haploid gametes?
One set of chromosomes
Haploid cells are crucial for maintaining chromosome number during fertilization.
What is fertilization?
The fusion of gametes from two parents
Fertilization results in the formation of a diploid organism.
What does fertilization lead to?
New, diploid offspring
This process restores the diploid state.
What is a key outcome of sexual reproduction?
Genetic variation
Genetic variation refers to differences between parents and offspring.
How do offspring inherit chromosomes from their parents?
One set from each parent
This results in a mixture of chromosomes and alleles.
What contributes to genetic variation among siblings?
Random selection of chromosomes from homologous pairs
Each gamete contains a different combination of chromosomes.
Fill in the blank: Diploid organisms produce _______ for reproduction.
gametes
Gametes are essential for sexual reproduction.
True or False: All sexually reproducing organisms are haploid.
False
Many sexually reproducing organisms are diploid.
What is the effect of only including one chromosome from each homologous pair in gametes?
Increases genetic diversity
This process ensures that siblings can inherit different combinations of alleles.
What affects an organism’s traits?
Genes
Genes are segments of DNA that encode for traits.
What are variations of genes called?
Alleles
Alleles can lead to different expressions of a trait.
How many alleles do many organisms have for each gene?
Two
One allele is inherited from each parent.
What is the term for an organism’s combination of alleles?
Genotype
The genotype determines potential traits.
What are the two types of genotypes?
Homozygous and heterozygous
Homozygous has two identical alleles, while heterozygous has two different alleles.
What is a homozygous genotype?
Two of the same alleles
Example: AA or aa.
What is a heterozygous genotype?
Two different alleles
Example: Aa.
What is a phenotype?
An observable version of a trait
The phenotype results from the organism’s genotype.
What determines an organism’s phenotype?
Combination of alleles
The phenotype reflects the genetic makeup.
What are the two types of alleles?
Dominant and recessive
These alleles interact to determine phenotypes.
How does a dominant allele affect phenotype?
Determines the phenotype even if a recessive allele is present
Dominant alleles are represented by uppercase letters.
How does a recessive allele affect phenotype?
Only determines the phenotype if no dominant allele is present
Recessive alleles are represented by lowercase letters.
What is a Punnett square?
A model that represents a cross between two organisms
It helps predict offspring genotypes and phenotypes.
What does a Punnett square help predict?
Likelihood of certain offspring genotypes and phenotypes
Predictions are based on the genotypes of the parents.
