biology Flashcards
What is the role of DNA and what does it stand for?
DNA stands for deoxyribonucleic acid and is the blueprint for controlling the characteristics of organisms
Describe the shape of a DNA molecule and identify the components of the polynucleotide chain
DNA molecule has a double strand helix structure and the polynucleotide chain alternates with a deoxyribose sugar and phosphate molecule.
List the names of the nitrogen base pairs in DNA
Thymine - Adenine
guanine - cytosine
What do the sequence of base pars determine
Characteristics of organisms are determined by the sequence of base pairs
What are chromosomes?
Long thin threadlike structure in the nucleus of a cell. Made from DNA.
What are genes?
A unit of inheritance giving instructions for a cell on how to make one type of protein.
What are proteins?
Chemicals in living things made of a chain of amino acids. Have many jobs in living things.
What are DNA?
The chemical that carries the genetic code which controls how an organism develops.
How many pairs are in a human somatic cell?
23 pairs
What are the parts of a chromosome?
2 sister chromatids
Centromere
What is a karyotype and what is the purpose of it?
Karyotyping classifies the chromosome according to its shape and size.
Uses:
- determination of sex
- determination of species
- detection of any chromosomal defects
Describe the role of a gene and its location.
The role of a gene is determining the characteristic of an organism. Each gene has a specific location on a chromosome called locus.
What is the purpose of mitosis?
Mitosis is useful for growth, maintenance and replacement of worn out cells. It only happens to body cells.
What is the purpose of meiosis?
Meiosis is useful as it is involved in production of gametes (sperm and ovum). Only occurs in gonads.
What is the difference between diploids and haploids
Haploid chromosome set occurs in eukaryotes when a sex cell or gamete is produced. This cell contains half of the genetic material, or chromosomes, of its parent cell. A diploid chromosome set occurs in most eukaryotes in somatic cells – that is, non-sex cells.
How does sexual reproduction work?
Sexual reproduction requires the fusion of a male gamete and a female gamete (fertilisation), each
containing genetic information that influences the offspring’s characteristics.
Why do variation in offspring occur?
Variation in offspring occurs due to random assortment of chromosomes and crossing over during
meiosis and random fusion of gametes during fertilisation.
Define mutations and describe how they arise.
A mutation is a change in the DNA base sequence. It happens when DNA is duplicated. It is a spontaneous and permanent change that can cause illness, allergic reactions or even death.
Distinguish gene and chromosomal mutations
In gene mutation, there are only 3 different ways it mutates which are substitution, deletion and insertion. On the other hand, chromosomal mutation can be manifested due to deletion, duplication, inversion, and translocation.
Describe non-disjunction mutations
Non-disjunction is when chromosomes do not separate correctly during cell division. Caused by too many autosomes, too few sex chromosomes or too many sex chromosomes
how does turner syndrome occur and what are some symptoms?
Turner syndrome (also known as monosomy X), is when missing an X chromosome in female. In males not possible because Y chromosome too small and would die.
how does Klinefelter syndrome occur and what are some symptoms?
Klinefelter is when someone has too many sex chromosomes. This is when male inherits 2 X chromosomes in addition to his Y chromosome.
how does down syndrome occur and what are some symptoms?
Down syndrome is when someone has too many autosomes. They have an extra chromosome in chromosome 21.
