Unit One: Genetic Processes Flashcards
What purpose does DNA serve?
It serves as the genetic blueprint that gives the instructions for building and maintaining an organism
What are the 3 parts of a nucleotide?
Sugar (deoxyribose), a phosphate group, and a nitrogenous base
What are the four types of nitrogenous bases?
Thymine, adenine, cytosine, and guanine
Which bases pair together?
Adenine + thymine and cytosine + gucinine
What is the shape of a DNA sequence called?
A double helix
What is the backbone of the double helix made up of?
Sugar and phosphate
What is the definition of heredity?
The passing of traits from one generation to the next through genetic information
What is a nucleotide?
The individual units that make up the structure of DNA ( made of sugar, phosphate group, and a nitrogenous base)
What is a base pairing?
The specific combination of nitrogenous bases
What are chromosomes?
The most condensed form of DNA and proteins
What is a chromatid?
One half of a duplicated chromosome
What is a sister chromatid?
Two identical chromatids that make up a duplicated chromosome
What is a centromere?
The region on a chromosome where two sister chromatids are joined
What are genes?
Segments of DNA that carry the instructions for making specific proteins and determining traits
What are traits?
Characteristics/ features of an organism that are determined by its DNA
What happens during the g 1 phase?
The cell grows and carries out normal functions, preparing for DNA replication
What happens during the s phase?
DNA is replicated, resulting in two identical sets of chromosomes
What happens during the g 2 phase?
The cell continues to grow and prepares for cell division
What happens during mitosis?
Nucleus and cytoplasm divide to produce two identical daughter cells
What happens during the g 0 phase?
A non dividing phase where cells are not actively progressing through the cell cycle
What happens during prophase?
The nucleus is still intact, chromosomes are condensing and visable
What happens during metaphase?
Chromosomes line up in the middle of the cell, nucleus is gone
What happens during anaphase?
The chromatids are moving towards opposite poles of the cell wall via spindles
What happens during telophase?
The chromosomes are at separate poles ans new nuclei are forming
What is cytokenesis?
Cytokenesis is when the cytoplasm splits, creating two new complete cells
What are somatic cells?
Somatic cells are any cells of an organism that are not reproductive cells
What are gametes?
Gametes are sex cells (sperm and egg)
What is meiosis?
A type of cell division that produces 4 genetically different daughter cells with half the number of chromosomes as the parent
What are homologous chromosomes?
Pairs of chromosomes that are similar in size, shape and have the same genes
Where do the two homologous chromosomes come from?
One comes from your mother, the other comes from your father
Essentially, how does meiosis work?
Meiosis is essentially mitosis twice
What is the difference between a diploid and a haploid?
A diploid has paired sets of chromosomes, a haploid has a single set of chromosomes
What is crossing over?
When homologous chromosomes swap random sections of their DNA with each other
What is independent assortment?
When homologous chromosomes randomly orient themselves on either side of the center line
What is gametogenesis?
The process of creating gametes through meiosis
What are the two kinds of gameotogenesis?
Spermatogenesis and Oogenesis
What happens at the end of spermatogenesis?
Spermatogenesis produced 4 unique haploid spermatids
What happens at the ends of oogenesis?
At the end, one unique egg and 3 polar bodies are made( polar bodies are made to provide egg with cytoplasm
What is nondisjunction?
When chromosomes separate improperly, leading to an uneven distribution of chromosomes among cells
What is a karyotype?
An image of the chromosomes in their homologous pairs arranged by shape and size
What is a gene?
A portion of DNA that determines certain traits of an organism
What is an allele?
An alternate form of a gene
What is the difference between homologous chromosomes and heterozygous chromosomes?
Homologous chromosomes contain the same allele for the same gene. Heterozygous chromosomes contain different alleles for a particular gene
What is a dominant allele?
If it is present, it will be expressed
What is a recessive allele?
The allele is only expressed if there is no dominant allele present
What does the law of segregation state?
- Organisms inherit two copies of each gene, one from each parent
- Organisms donate only one copy of each gene to their gametes. During meiosis, the two copies of each gene Separate or segregate
What are non Mendelian inheritance patterns?
Inheritance patterns that don’t follow complete dominance
Define incomplete dominance
The dominant allele doesn’t completely mask the recessive allele. Instead, there is a blending of the two alleles
Define codominance
Both alleles are simultaneously expressed, neither are dominant or recessive. No blending occurs
Define multiple alleles
Some genes have more than 2 alleles
Describe pleiotropy
Describes genes that affect many traits, not just a single characteristic
Define polygenic traits
Single traits that are determined by several genes
Define lethal alleles
When some combination results results in the death of an organism
Define epistasis
When the presence of alleles for one gene influences the expression of alleles for another gene
Define sex linked traits
Genes located in the sex chromosomes.
What is a dihybrid cross?
It examines the genetic makeup of offspring from parents that differ on two traits
What is a pedigree?
A pedigree is a graph showing a family’s genetic history that is used to track the inheritance of traits/ genetic conditions
What does a filled in section of a pedigree mean?
It means the individual is affected with whatever you are tracking
