Genetics Terminology Flashcards
Heredity Definition
The passing of genetic traits from parent to offspring.
What is Genetics?
From ‘genesis’, the area of biology concerned with how information in organisms is passed from parents to offspring/progeny.
What did 19th century scientists show?
That there were factors within organisms that determined their characteristics and that these factors were heritable.
What was the word “gene” used to describe?
These factors
What did 20th century scientists show?
That these genes were made up of DNA.
What do human cells contain?
46 DNA molecules (chromosomes) with approximately 23,000 genes.
What is understood today?
That genes are segments of a DNA molecule that influence or directly code for specific traits.
What is a chromosome made of? What does it contain?
-Made of DNA and protein.
-Contains genes
What are genes?
Heritable factors that control specific characteristics.
What are alleles?
Different forms of a specific gene.
What is a gene locus?
The specific position of a gene on a chromosome.
What do all individuals of a species do?
Carry the same genes at the same loci on the same chromosomes.
Where are chromosomes contained?
In the nucleus of all eukaryotic cells.
What do chromosomes vary widely in?
Shape, number and size.
How do chromosomes exist in multicellular organisms?
In sets
What is contained in a haploid nuclei?
One of each chromosome type.
In humans, how many chromosomes do haploid cells contain?
23 chromosomes
What are haploid cells?
Sex cells (gametes) that fuse together during sexual reproduction - egg and sperm.
What does “haploid” mean?
“Half” of a full set of chromosomes.
What do diploid nuclei contain?
Two of each chromosome type (and so 2 copies of each gene)
In humans, how many chromosomes do diploid cells contain?
In humans, diploid cells contain 46 chromosomes (2 x 23).
What happens during fertilization?
Haploid sperm and egg fuse in fertilization to produce diploid zygote, which then divides by mitosis to form embryo.
What are diploid cells?
Body cells (somatic cells)
What do males only have?
One copy of each gene on the X and Y sex chromosomes.
What do eukaryotic cells contain?
Different types of chromosomes with different genes.
What do chromosomes differ in?
Length and position of the centromere.
How many different types of chromosomes do humans have?
23
What are the different types of chromosomes that humans have divided into?
- 22 pairs of Autosomes (1-22).
- 1 pair of Sex Chromosomes (23).
What does each chromosome carry?
A different set of genes in a specific order.
What is the location of each gene on the chromosome called?
The gene locus.
What is a fundamental feature that defines a species?
Chromosome number
What do all members of a species have?
The same chromosome number
When does chromosome numbe tend to be conserved?
Across millions of years of evolution.
In rare cases, what can happen?
Chromosomes can fuse together or split to change chromosome number of a species.
During human evolution, what happened?
Two ancestral ape chromosomes fused to form modern day Chromosome 2 (as a result, humans have 23 types of chromosomes, while ape species have 24.
Where are genes distributed?
Amongst an organism’s chromsomes.
What is the location of a gene on a chromosome called?
The locus of the gene
What do all members of a species have?
The same chromosome number with the same genes in the same loci along their chromosomes.
What is a genome?
The whole genetic information of an organism.
What does the genome consist of in humans?
46 chromosomes in nucleus plus mitochondrial DNA
What does the genome consist of in plants?
Chromosomes in the nucleus plus DNA in the mitochondria and chloroplasts.
What does the genome consist of in prokaryotes?
Much smaller genome consisting of DNA in a circular chromosome and any plasmids.
When did the Human Genome Project begin and what did it produce?
The Human Genome Project (HGP) began in 1990 and produced a full copy of a human genome in 2003.
All human genomes vary due to what?
SNPs
What is identical among all humans?
99.9% of the genome
Public/private competition and collaboration drove incredibly rapid what?
Biotech research and development
What did HGP produce?
A vast set of data in the form of the approximately 3.2 billion base letter sequence of human DNA
What are scientists still in the process of?
Decoding these sequences to ID specific genes
How many genes were identified?
Approximately 23,000 genes (much fewer than predicted)
What was discovered?
Much of the genome is NOT transcribed
What were highly-repetitive sequences originally called? Why?
“Junk DNA” but now recognized as having a number of key functions.
What are two modes of reproduction?
-Asexual
-Sexual
What happens during asexual reproduction? (3 points)
- New individual is produced from a single parent by cell division.
- Two daughters cells receive one copy of each chromosome.
- Two daughter cells are genetically identical to one another and the parent cell.
What happens during sexual reproduction? (3 points)
- New individual is produced from the fusion of two sex cells
- Sex cells usually come from two different organisms
- Offspring are not genetically identical to one another
What are the stages of asexual reproduction in the cell cycle? What happens in each?
- Mitosis: Stage of the cell cycle during which the genetic material in the nucleus of a eukaryotic cell is divided equally into two nuclei.
-Cytokinesis: Nuclear division
-Interphase: Cell growth, normal functions, chromatin is formed.
What are the six stages of mitosis?
-G2 of Interphase
-Prophase
-Prometaphase
-Metaphase
-Anaphase
-Telophase and Cytokinesis
What is cloning? (4 points)
-A mode of asexual reproduction
-Process of forming identical offspring from a single cell or tissue
-Form of biotechnology
-There are ethics concerns
