Cell Division and Inheritance Flashcards
What is the function of the nucleus
Controls and regulates the activities of the cell, produces ribosomes and contains DNA
Define the term Alleles
Are alternative versions of genes
Define homozygous alleles
Have identical information for a trait
Define heterozygous alleles
Have different information for a trait
Name the two different types of cell division
Somatic cell division & reproductive cell division
Describe somatic cell division
Aims to replicate cells to replace dead or injured cells or add new cells. Occurs through mitosis & cytokinesis (you dont have sex with your toes, mytoesis)
Describe reproductive cell division
Aim is to produce the gamete cells (sperma nd oocyte). Occurs through meiosis (me=my sis=sex)
How many chromosomes are there in each somatic cell in somatic cell division? And where does cell division occur?
46 chromosomes and occurs through three main phases, Interphase, Mitosis and cytokinesis
How many chromosomes are there in each reproductive cell in cell reproductive cell division? and where does cell division occur?
23 chromosomes and occurs in the testes and ovaries
Explain how genetic variation occurs
When two homologous chromosomes partner up they exchange genetic material between non-sister chromatids
Define cancer
Cancer is the group of diseases that results from uncontrolled or abnormal cell proliferation
Define the term malignant tumour
Malignant tumours undergo metastases (the spread of cancerous cells to other parts of the body)
Define the term benign tumour
Benign tumours do not metastasise (they do not spread)
Name the type of cancer cell that arises from epithelial tissue
Carcinoma arises from epithelial tissue
Name the type of cancer cell that arises from melanocytes
Melanoma arises from melanocytes
Name the type of cancer cell that arises from lymphatic tissue
Lymphoma arises from lymphatic tissue
Name the type of cancer cell that arises from leukocytes
Leukemia arises from leukocytes
State three causes of cancer
Environmental agents like cigarette tar or UV light.
Viruses like HPV stimulate abnormal cell proliferation
Genes - abnormalities of genes that control and regulate cell division
Define inheritance
Inheritance is the passage of hereditary traits from one generation to another
Define genetics
Genetics is the branch of biology that deals with inheritance.
Define genotype
Genotype is the genetic makeup of an individual
E.g. Pp
Define phenotype
Phenotype is the physical characteristics determined by the genotype & the environment
E.g. brown hair, blue eyes
Define mutation
Mutation is a permanent, heritable change in a gene that causes it to have a different effect than it had previously.
Define autosomes
Autosomes are any chromosomes other than a sex chromosomes.
Define x-linked (sex) chromosomes
Sex chromosomes are the 23rd pair
In females, the 23rd pair consists of XX
In males, the 23rd pair consists of XY
Explain what a dominant allele is. (include how the genotype would be written)
A dominant allele is an allele that is always expressed, or evident, in a person. It does this by over-riding the influence of the corresponding allele on the other homologous chromosome. E.g. Pp
Explain what a recessive allele is. (include how the genotype would be written)
Recessive allele is an allele that is completely hidden or masked by the presence of a dominant allele. A recessive allele is only expressed when no dominant allele is present. E.g. pp (homozygous recessive)
Explain the genetic condition autosomal dominant and give an example
Caused by a mutation of a single gene on a chromosome. One heterozygous parent will have a 50% chance of having a child with a disease. Pp Huntington’s disease is an example of an autosomal dominant genetic condition.
Explain the genetic condition autosomal recessive and give an example
Caused by mutations of two gene pairs on a chromosome. pp Cystic fibrosis is an example of an autosomal recessive genetic condition
Explain the genetic condition x-linked recessive and give and example
Caused by mutation on the X chromosome and is more common in men as they only have one X chromosome. Colour blindness is an example of a x-linked recessive genetic condition.
Define multiple allele inheritance and give one example of a genetic trait carried by this type of inheritance
Some genes have more than two alternate forms. eg coding for blood type.
Define complex inheritance and give one example of a genetic trait carried by this type of inheritance
Most inherited traits are not controlled by one gene but by the combined effects of two or more genes or combined effects of many genes and environmental factors. eg skin or hair colour
Describe the difference between autosomes & sex chromosomes
There are 23 pairs of chromosomes. 22 pairs of chromosomes are homologous and have the same appearance in both males and females and are called autosomes. Whereas sex chromosomes are the final pair which make up the 23 pairs and consist of XX (females) and XY (males)
Explain why x-linked conditions primarily affect males
X-linked conditions primarily effect males because there are no counterbalancing dominant genes on the Y-chromosome
Give two examples of x-linked conditions
Red-green colour blindness and hemophilia
Explain the term trisomy and give an example
Trisomy has an extra chromosome with one of the pairs - down’s syndrome has 3 21st chromosomes
Explain the term monosomy and give an example
Monosomy is missing a chromosome from one of the pairs for example turners syndrome
